Stub minimization using duplicate sets of signal terminals in assemblies without wirebonds to package substrate

ABSTRACT

A microelectronic assembly can include a circuit panel having first and second panel contacts at respective first and second surfaces thereof, and first and second microelectronic packages each having terminals mounted to the respective panel contacts. Each package can include a microelectronic element having a face and contacts thereon, a substrate having first and second surfaces, and terminals on the second surface configured for connecting the package with an external component. The terminals can include first terminals at positions within first and second parallel grids. The first terminals can be configured to carry address information usable by circuitry within the package to determine an addressable memory location from among all the available addressable memory locations of a memory storage array within the microelectronic element. Signal assignments of the first terminals in the first grid can be a mirror image of signal assignments of the first terminals in the second grid.

RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/439,228, filed Apr. 4, 2012, which claims the benefit of thefiling date of U.S. Provisional Patent Application Nos. 61/542,488,61/542,495, and 61/542,553, all filed Oct. 3, 2011, and 61/600,483,filed Feb. 17, 2012, the disclosures of all of which are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

The subject matter of the present application relates to microelectronicpackages and assemblies incorporating microelectronic packages.

Semiconductor chips are commonly provided as individual, prepackagedunits. A standard chip has a flat, rectangular body with a large frontface having contacts connected to the internal circuitry of the chip.Each individual chip typically is contained in a package having externalterminals connected to the contacts of the chip. In turn, the terminals,i.e., the external connection points of the package, are configured toelectrically connect to a circuit panel, such as a printed circuitboard. In many conventional designs, the chip package occupies an areaof the circuit panel considerably larger than the area of the chipitself. As used in this disclosure with reference to a flat chip havinga front face, the “area of the chip” should be understood as referringto the area of the front face.

In “flip chip” designs, the front face of the chip confronts the face ofa package dielectric element, i.e., substrate of the package, and thecontacts on the chip are bonded directly to contacts on the face of thesubstrate by solder bumps or other connecting elements. In turn, thesubstrate can be bonded to a circuit panel through the externalterminals that overlie the substrate. The “flip-chip” design provides arelatively compact arrangement. Some flip-chip packages are commonlyreferred to as “chip-scale packages” in which each package occupies anarea of the circuit panel equal to or slightly larger than the area ofthe chip's front face, such as disclosed, for example, in certainembodiments of commonly-assigned U.S. Pat. Nos. 5,148,265; 5,148,266;and 5,679,977, the disclosures of which are incorporated herein byreference. Certain innovative mounting techniques offer compactnessapproaching or equal to that of conventional flip-chip bonding.

Size is a significant consideration in any physical arrangement ofchips. The demand for more compact physical arrangements of chips hasbecome even more intense with the rapid progress of portable electronicdevices. Merely by way of example, devices commonly referred to as“smart phones” integrate the functions of a cellular telephone withpowerful data processors, memory and ancillary devices such as globalpositioning system receivers, electronic cameras, and local area networkconnections along with high-resolution displays and associated imageprocessing chips. Such devices can provide capabilities such as fullinternet connectivity, entertainment including full-resolution video,navigation, electronic banking and more, all in a pocket-size device.Complex portable devices require packing numerous chips into a smallspace. Moreover, some of the chips have many input and outputconnections, commonly referred to as “I/Os.” These I/Os must beinterconnected with the I/Os of other chips. The components which formthe interconnections should not greatly increase the size of theassembly. Similar needs arise in other applications as, for example, indata servers such as those used in internet search engines whereincreased performance and size reduction are needed.

Semiconductor chips containing memory storage arrays, particularlydynamic random access memory chips (DRAMs) and flash memory chips, arecommonly packaged in single- or multiple-chip packages and assemblies.Each package has many electrical connections for carrying signals,power, and ground between terminals and the chips therein. Theelectrical connections can include different kinds of conductors such ashorizontal conductors, e.g., traces, beam leads, etc., which extend in ahorizontal direction relative to a contact-bearing surface of a chip,vertical conductors such as vias, which extend in a vertical directionrelative to the surface of the chip, and wire bonds that extend in bothhorizontal and vertical directions relative to the surface of the chip.

Conventional microelectronic packages can incorporate a microelectronicelement that is configured to predominantly provide memory storage arrayfunction, i.e., a microelectronic element that embodies a greater numberof active devices to provide memory storage array function than anyother function. The microelectronic element may be or include a DRAMchip, or a stacked electrically interconnected assembly of suchsemiconductor chips. Typically, all of the terminals of such package areplaced in sets of columns adjacent to one or more peripheral edges of apackage substrate to which the microelectronic element is mounted.

For example, in one conventional microelectronic package 12 seen in FIG.1, three columns 14 of terminals can be disposed adjacent a firstperipheral edge 16 of the package substrate 20 and three other columns18 of terminals can be disposed adjacent a second peripheral edge 22 ofthe package substrate 20. A central region 24 of the package substrate20 in the conventional package does not have any columns of terminals.FIG. 1 further shows a semiconductor chip 11 within the package havingelement contacts 26 on a face 28 thereof which are electricallyinterconnected with the columns 14, 18 of terminals of the package 12through wire bonds 30 extending through an aperture, e.g., bond window,in the central region 24 of package substrate 20. In some cases, anadhesive layer 32 may be disposed between the face 28 of themicroelectronic element 11 and the substrate 20 to reinforce themechanical connection between the microelectronic element and thesubstrate, with the wire bonds extending through an opening in theadhesive layer 32.

In light of the foregoing, certain improvements in the positioning ofterminals on microelectronic packages can be made in order to improveelectrical performance, particularly in assemblies which include suchpackages and a circuit panel to which such packages can be mounted andelectrically interconnected with one another.

BRIEF SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a microelectronicassembly can include a circuit panel having first and second opposedsurfaces and first and second panel contacts at the first and secondsurfaces, respectively, and first and second microelectronic packageseach having terminals mounted to the respective panel contacts. Eachmicroelectronic package can include a microelectronic element having aface and a plurality of element contacts thereon, a substrate havingfirst and second opposed surfaces, and a plurality of terminals on thesecond surface configured for connecting the microelectronic packagewith at least one component external to the package. The microelectronicelement can embody a greater number of active devices to provide memorystorage array function than any other function.

The substrate can have a set of substrate contacts on the first surfacefacing the element contacts of the microelectronic element and joinedthereto. The terminals can be electrically connected with the substratecontacts and can include first terminals arranged at positions withinfirst and second parallel grids. The first terminals of each of thefirst and second grids can be configured to carry address informationusable by circuitry within the microelectronic package to determine anaddressable memory location from among all the available addressablememory locations of a memory storage array within the microelectronicelement. The signal assignments of the first terminals in the first gridcan be a mirror image of the signal assignments of the first terminalsin the second grid.

In a particular embodiment, the first terminals of each of the first andsecond grids of each microelectronic package can be configured to carryall of the address information usable by the circuitry within therespective microelectronic package to determine the addressable memorylocation. In one example, the first terminals of each of the first andsecond grids of each microelectronic package can be configured to carryinformation that controls an operating mode of the microelectronicelement of the respective microelectronic package. In an exemplaryembodiment, the first terminals of each of the first and second grids ofeach microelectronic package can be configured to carry all of thecommand signals transferred to the respective microelectronic package,the command signals being write enable, row address strobe, and columnaddress strobe signals.

In one embodiment, the first terminals of each of the first and secondgrids of each microelectronic package can be configured to carry clocksignals transferred to the respective microelectronic package, the clocksignals being clocks used for sampling signals carrying the addressinformation. In a particular example, the first terminals of each of thefirst and second grids of each microelectronic package can be configuredto carry all of the bank address signals transferred to the respectivemicroelectronic package. In an exemplary embodiment, the first terminalsin the second grid of the first package can be connected through thecircuit panel to the first terminals in the first grid of the secondpackage. The first terminals of the second grid of the first package canbe aligned within one ball pitch of the corresponding first terminals towhich they are connected of the first grid on the second package in xand y orthogonal directions parallel to the first and second circuitpanel surfaces.

In a particular example, the grids can be aligned with one another inthe x and y orthogonal directions such that the terminals of the gridsare coincident with one another. In one embodiment, each position ofeach grid can be occupied by one of the terminals. In an exemplaryembodiment, at least one position of at least one of the grids may notbe occupied by a terminal. In a particular embodiment, at least half ofthe positions of the grids of the first and second packages can bealigned with one another in x and y orthogonal directions parallel tothe first surface of the circuit panel. In one example, the grids of thefirst and second microelectronic packages can be functionally andmechanically matched. In a particular example, a length of a stub of atleast one of electrical connections between one of the first terminalsof the first microelectronic package and a corresponding one of thefirst terminals of the second microelectronic package can be less thanseven times a minimum pitch of the first terminals of each of themicroelectronic packages.

In an exemplary embodiment, at least some of the electrical connectionsthrough the circuit panel between the first terminals of the first andsecond microelectronic packages can have an electrical length ofapproximately a thickness of the circuit panel. In one example, thetotal combined length of the conductive elements connecting each pair ofelectrically coupled first and second panel contacts exposed at thefirst and second surfaces of the circuit panel can be less than seventimes a smallest pitch of the panel contacts. In a particularembodiment, the circuit panel can include a bus having a plurality ofconductors configured to carry all of the address informationtransferred to each of the microelectronic packages. The conductors canextend in a first direction parallel to the first and second surfaces.

In one example, each of the first and second grids of first terminals ofeach microelectronic package can have a single column. The circuit panelmay include no more than one routing layer for routing of the addressinformation between respective connection sites on the circuit panel atwhich the terminals of one or more of the microelectronic packages areelectrically connected. In a particular embodiment, each of the firstand second grids of first terminals of each microelectronic package canhave two parallel columns. The circuit panel may include no more thantwo routing layers for routing of the address information betweenrespective connection sites on the circuit panel at which the terminalsof one or more of the microelectronic packages are electricallyconnected.

In a particular embodiment, there may be no more than one routing layerfor routing of the address information between respective connectionsites on the circuit panel at which the terminals of one or more of themicroelectronic packages are electrically connected. In one embodiment,each microelectronic package can include a semiconductor elementelectrically connected to at least some of the respective terminals andthe microelectronic element in the respective microelectronic package.Each semiconductor element can be configured to at least one of:regenerate or at least partially decode at least one of addressinformation or command information received at one or more of theterminals of the respective microelectronic package for transfer to themicroelectronic element.

In an exemplary embodiment, the microelectronic element of eachmicroelectronic package can be a first microelectronic element, and theset of substrate contacts of each substrate can be a first set ofsubstrate contacts. Each microelectronic package can also include asecond microelectronic element having a face and a plurality of elementcontacts thereon. The second microelectronic element can embody agreater number of active devices to provide memory storage arrayfunction than any other function.

Each substrate can have a second set of substrate contacts on the firstsurface facing the element contacts of the respective secondmicroelectronic element and joined thereto. The terminals of therespective microelectronic package can be electrically connected withthe second set of substrate contacts. The first terminals of each of thefirst and second grids of each microelectronic package can be configuredto carry address information usable by circuitry within the respectivemicroelectronic package to determine an addressable memory location fromamong all the available addressable memory locations of a memory storagearray within the first and second microelectronic elements of therespective microelectronic package. In one example, the circuit panelcan include an element having a coefficient of thermal expansion (“CTE”)of less than 12 parts per million per degree Celsius (“ppm/° C.”). Thepanel contacts at the first and second surfaces can be connected by viasextending through the element. In a particular embodiment, the elementcan consist essentially of semiconductor, glass, ceramic or liquidcrystal polymer material.

In accordance with another aspect of the invention, a system can includea microelectronic assembly as described above and one or more otherelectronic components electrically connected to the microelectronicassembly. In a particular example, the system can also include ahousing, the microelectronic assembly and the one or more otherelectronic components being assembled with the housing. In oneembodiment, the microelectronic assembly can be a first microelectronicassembly, the system also including a second microelectronic assembly asdescribed above. In accordance with yet another aspect of the invention,a module can include a plurality of microelectronic assemblies asdescribed above, each microelectronic assembly mounted to, andelectrically connected with a second circuit panel for transport ofsignals to and from each microelectronic assembly.

In accordance with still another aspect of the invention, amicroelectronic assembly can include a circuit panel having first andsecond opposed surfaces and first and second panel contacts at the firstand second surfaces, respectively, and first and second microelectronicpackages each having terminals mounted to the respective panel contacts.Each microelectronic package can include a microelectronic elementhaving a face and a plurality of element contacts thereon, a substratehaving first and second opposed surfaces, and a plurality of terminalson the second surface configured for connecting the microelectronicpackage with at least one component external to the package. Themicroelectronic element can embody a greater number of active devices toprovide memory storage array function than any other function. Thesubstrate can have a set of substrate contacts on the first surfacefacing the element contacts of the microelectronic element and joinedthereto.

The terminals can be electrically connected with the substrate contactsand can include first terminals arranged at positions within first andsecond parallel grids. The first terminals of each of the first andsecond grids can be configured to carry a majority of the addressinformation usable by circuitry within the microelectronic package todetermine an addressable memory location from among all the availableaddressable memory locations of a memory storage array within themicroelectronic element. The signal assignments of the first terminalsin the first grid can be a mirror image of the signal assignments of thefirst terminals in the second grid. In one embodiment, the firstterminals of each of the first and second grids of each microelectronicpackage can be configured to carry at least three-quarters of theaddress information usable by the circuitry within the respectivemicroelectronic package to determine the addressable memory location.

In accordance with another aspect of the invention, a microelectronicassembly can include a circuit panel having first and second opposedsurfaces and first and second panel contacts at the first and secondsurfaces, respectively, and first and second microelectronic packageseach having terminals mounted to the respective panel contacts. Eachmicroelectronic package can include a microelectronic element having aface and a plurality of element contacts thereon, a substrate havingfirst and second opposed surfaces, and a plurality of terminals on thesecond surface configured for connecting the microelectronic packagewith at least one component external to the package. The microelectronicelement can embody a greater number of active devices to provide memorystorage array function than any other function.

The substrate can have a set of substrate contacts on the first surfacefacing the element contacts of the microelectronic element and joinedthereto. The terminals can be electrically connected with the substratecontacts and can include a first set of first terminals arranged in afirst individual column and second set of the first terminals arrangedin a second individual column. The first terminals of each of the firstand second grids can be configured to carry address information usableby circuitry within the microelectronic package to determine anaddressable memory location from among all the available addressablememory locations of a memory storage array within the microelectronicelement. The signal assignments of the first terminals in the first gridcan be symmetric about an axis extending between the first and secondgrids with respect to the signal assignments of the first terminals inthe second grid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating a conventional microelectronicpackage containing a DRAM chip.

FIG. 2 is a diagrammatic schematic diagram illustrating amicroelectronic assembly, e.g., a DIMM module, incorporating a circuitpanel and a plurality of microelectronic packages mounted opposite oneanother to first and second opposite surfaces thereof.

FIG. 3 is a sectional view further illustrating an electricalinterconnection between first and second microelectronic packages and acircuit panel in an assembly such as shown in FIG. 2.

FIG. 4 is a diagrammatic plan view further illustrating the electricalinterconnection between first and second microelectronic packages in anassembly such as shown in FIG. 2.

FIG. 5 is a diagrammatic plan view illustrating an arrangement andsignal assignment of terminals in a microelectronic package according toan embodiment of the invention.

FIG. 5A is a fragmentary view showing an alternate arrangement ofterminals for a portion of FIG. 5.

FIG. 6 is a sectional view through line 6-6 of FIG. 5 furtherillustrating the microelectronic package shown in FIG. 5.

FIG. 7 is a plan view further illustrating an arrangement of terminalsin accordance with the embodiment shown in FIGS. 5 and 6.

FIG. 8A is a sectional view illustrating a microelectronic assembly andfirst and second microelectronic packages electrically interconnectedtherewith in accordance with an embodiment of the invention.

FIG. 8B is a sectional view illustrating a microelectronic assembly andfirst and second microelectronic packages electrically interconnectedtherewith in accordance with an embodiment of the invention.

FIG. 8C is a sectional view illustrating a microelectronic assembly andfour microelectronic packages electrically interconnected therewith inaccordance with an embodiment of the invention.

FIG. 8D is a schematic diagram illustrating a microelectronic assemblyincluding a circuit panel and microelectronic packages electricallyconnected thereto, e.g., a memory module, among others, according to anembodiment of the invention.

FIG. 9 is a diagrammatic plan view illustrating an arrangement andsignal assignment of terminals in a microelectronic package according toan embodiment of the invention.

FIG. 10 is a diagrammatic plan view illustrating an arrangement andsignal assignment of terminals in a microelectronic package according toan embodiment of the invention.

FIG. 11 is a sectional view illustrating a wafer-level microelectronicpackage according to a variation of the embodiment shown in FIGS. 5-7.

FIG. 12 is a sectional view illustrating a microelectronic assembly andfirst and second microelectronic packages electrically interconnectedtherewith in accordance with an embodiment of the invention.

FIGS. 13 and 14 are a sectional view and a plan view illustrating amicroelectronic package according to a variation of the embodiment shownin FIGS. 5-7.

FIG. 15 is a plan view illustrating an alternative arrangement ofterminals on a microelectronic package according to a variation of theembodiment shown in FIGS. 13 and 14.

FIG. 16 is a plan view illustrating another alternative arrangement ofterminals on a microelectronic package according to a variation of theembodiment shown in FIGS. 13 and 14.

FIG. 17 is a plan view illustrating a microelectronic package accordingto a variation of the embodiment shown in FIGS. 5-7.

FIG. 18 is a plan view illustrating a microelectronic package accordingto a variation of the embodiment shown in FIGS. 13 and 14.

FIG. 19 is a plan view illustrating a microelectronic package accordingto a variation of the embodiment shown in FIG. 18.

FIG. 20 is a plan view illustrating a microelectronic package accordingto a variation of the embodiment shown in FIG. 19.

FIG. 21 is a sectional view illustrating a microelectronic packageincluding a stacked electrically connected assembly of semiconductorchips therein in accordance with an embodiment of the invention.

FIG. 22A is a sectional view illustrating a microelectronic packageincluding a stacked electrically connected assembly of semiconductorchips therein in accordance with an embodiment of the invention.

FIG. 22B is a sectional view illustrating a microelectronic packageaccording to a variation of the embodiment shown in FIG. 22A.

FIG. 23 is a sectional view illustrating a microelectronic packageaccording to a variation of the embodiment shown in FIG. 22A.

FIG. 24 is a sectional view illustrating a microelectronic packageaccording to another variation of the embodiment shown in FIG. 22A.

FIG. 25 is a sectional view illustrating a microelectronic packageaccording to yet another variation of the embodiment shown in FIG. 22A.

FIG. 26A is a diagrammatic plan view illustrating an arrangement andsignal assignment of terminals in a microelectronic package according toan embodiment of the invention.

FIG. 26B is a plan view further illustrating an arrangement of terminalsin accordance with the embodiment shown in FIG. 26A.

FIG. 26C is a sectional view through line 26C-26C of FIG. 26A furtherillustrating the microelectronic package shown in FIG. 26A.

FIG. 26D is a plan view illustrating an alternative arrangement ofcontacts on a microelectronic element according to a variation of theembodiment shown in FIGS. 26A-26C.

FIG. 27 is a sectional view illustrating a microelectronic assembly andfirst and second microelectronic packages electrically interconnectedtherewith in accordance with an embodiment of the invention.

FIG. 28 is a schematic sectional view illustrating a system according toan embodiment of the invention.

FIG. 29 is a schematic sectional view illustrating a system according toan embodiment of the invention.

DETAILED DESCRIPTION

In view of the illustrative conventional microelectronic package 12described relative to FIG. 1, the inventors have recognized improvementswhich can be made that may help improve the electrical performance of amicroelectronic package incorporating a memory storage array chip, and amicroelectronic assembly that incorporates such microelectronic package.

Improvements can be made particularly for use of a microelectronicpackage when provided in an assembly such as shown in FIGS. 2-4, inwhich a package 12A is mounted to a surface of a circuit panel withanother like package 12B mounted opposite thereto on an opposite surfaceof the circuit panel. The packages 12A, 12B typically are functionallyand mechanically equivalent to one another. Other pairs 12C and 12D; and12E and 12F, of functionally and mechanically equivalent packagestypically are also mounted to the same circuit panel 34. The circuitpanel and the packages assembled thereto may form a portion of anassembly commonly referred to as a dual in-line memory module (“DIMM”).The packages in each oppositely mounted pair of packages, e.g., packages12A, 12B, connect to contacts on opposite surfaces of the circuit panelso that the packages in each pair overlie one another typically by morethan 90% of their respective areas. Local wiring within the circuitpanel 34 connects terminals, e.g., the terminals labeled “1” and “5” oneach package to global wiring on the circuit panel. The global wiringincludes the signal conductors of a bus 36 used to conduct some signalsto connection sites on the circuit panel 34 such as sites I, II and III.For example, the packages 12A, 12B are electrically connected to the bus36 by local wiring coupled to a connection site I, the packages 12C, 12Dare electrically connected to the bus by local wiring coupled toconnection site II, and the packages 12E, 12F are electrically connectedto the bus by local wiring coupled to connection site III.

The circuit panel 34 electrically interconnects the terminals of therespective packages 12A, 12B using local interconnect wiring thatappears similar to a crisscross or “shoelace” pattern in which aterminal labeled “1” near one edge of package 12A connects through thecircuit panel 34 to a terminal labeled “1” of package 12B near the sameedge 16 of package 12B. However, the edge 16 of package 12B as assembledto circuit panel 34 is far from the edge 16 of package 12A. FIGS. 2-4further shows that a terminal labeled “5” near an edge 22 of package 12Ais connected through the circuit panel 34 to a terminal labeled “5” ofpackage 12B near the same edge 22 of package 12B. In assembly 38 theedge 22 of package 12A is far from the edge 22 of package 12B.

Connections through the circuit panel between terminals on each package,e.g., the package 12A, to the corresponding terminals on the packagemounted opposite thereto, i.e., the package 12B, are fairly long. Asfurther seen in FIG. 3, in such assembly of like microelectronicpackages 12A, 12B, the circuit panel 34 may electrically interconnect asignal conductor of the bus 36 with the terminal of package 12A marked“1” and the corresponding terminal of package 12B marked “1”, when thesame signal from the bus is to be transmitted to each package.Similarly, the circuit panel 34 may electrically interconnect anothersignal conductor of the bus 36 with the terminal of package 12A marked“2” and the corresponding terminal of package 12B marked “2”. The sameconnection arrangement may also apply to other signal conductors of thebus and corresponding terminals of each package.

Local wiring between the bus 36 on the circuit panel 34 and each packageof the respective pair of packages, e.g., packages 12A, 12B (FIG. 2) ata connection site I of the board can be in form of unterminated stubs.Such local wiring when relatively long may in some cases impact theperformance of the assembly 38 as discussed below. Moreover, the circuitpanel 34 also requires local wiring to electrically interconnect certainterminals of other packages: the pair of packages 12C and 12D, and thepair of packages 12E and 12F to the global wiring of the bus 36, andsuch wiring can also impact the performance of the assembly in the sameway.

FIG. 4 further illustrates the interconnection between microelectronicpackages 12A, 12B of respective pairs of terminals assigned to carrysignals “1”, “2”, “3”, “4”, “5”, “6”, “7”, and “8”. As seen in FIG. 4,all of the columns 14, 18 of terminals are exposed near the edges 16,22, respectively, of each package 12A, 12B, rather than in a centralregion 24 of the surface of the substrate, the wiring needed to traversethe circuit panel 34 in a direction 40 transverse to the direction 42 inwhich the columns 14, 18 of terminals extend can be quite long. Inrecognition that the length of a DRAM chip can be in the range of tenmillimeters on each side, the length of the local wiring in a circuitpanel 34 in an assembly 38 seen in FIGS. 2-4 required for some signalsto route the same signal to the corresponding terminals of twooppositely mounted packages 12A, 12B can range between five and tenmillimeters and may typically be about seven millimeters.

In some cases, relatively long unterminated wiring on a circuit panelwhich connects the terminals of a package may not severely impact theelectrical performance of the assembly 38. However, when a signal istransferred from a bus 36 of the circuit panel to each of multiple pairsof packages connected to the circuit panel as shown in FIG. 2, theinventors recognize that the electrical lengths of the stubs, i.e., thelocal wiring, that extend from the bus 36 to the terminal connectedthereto on each package potentially impacts the performance of theassembly 38. Signal reflections on the unterminated stubs can travel inthe reverse direction from the connected terminals of each package backonto the bus 36, and thus degrade the signals being transferred from thebus 36 to the packages. The impacts may be tolerable for some packagescontaining microelectronic elements of current manufacture. However, inpresent or future assemblies which operate with increased signalswitching frequencies, low voltage swing signals or both, the inventorsrecognize that the impacts can become severe. For these assemblies,settling time, ringing, jitter, or intersymbol interference of atransmitted signal may increase to an unacceptable degree.

The inventors further recognize that the electrical lengths of theunterminated stubs are usually longer than the local wiring thatconnects the bus 36 on the circuit panel with the terminals of thepackages mounted thereto. Unterminated wiring within each package fromthe package terminals to the semiconductor chip therein adds to thelengths of the stubs.

In a specific example, the bus 36 is a command-address bus of anassembly having a predominant memory storage array function such as aDIMM. The command-address bus 36 can be configured to carry addressinformation transferred to the microelectronic packages that is usableby circuitry within the packages, e.g., row address and column addressdecoders, and bank selection circuitry, if present, to determine anaddressable memory location from among all the available addressablememory locations of a memory storage array within a microelectronicelement in the packages. The command-address bus 36 can be configured tocarry the above-noted address information to connection sites, e.g.,sites I, II, and III shown in FIG. 2. These above-noted addressinformation can then be distributed by local wiring to respective setsof panel contacts on opposite surfaces of the circuit panel, to whichpackages 12A, 12B, 12C, 12D, 12E and 12F are connected.

In a particular example, when the microelectronic element is or includesa DRAM chip, command-address bus 36 can be configured to carry all of agroup of signals of a command-address bus of the microelectronicelement, i.e., command signals, address signals, bank address signalsand clock signals that are transferred to the microelectronic packages,wherein the command signals include write enable, row address strobe,and column address strobe signals, and the clock signals are clocks usedfor sampling the address signals. While the clock signals can be ofvarious types, in one embodiment, the clock signals carried by theseterminals can be one or more pairs of differential clock signalsreceived as differential or true and complement clock signals.

Accordingly, certain embodiments of the invention described hereinprovide a microelectronic package configured so as to permit the lengthsof stubs to be reduced when first and second such packages are mountedopposite one another on opposite surfaces of a circuit panel, e.g., acircuit board, module board or card, or flexible circuit panel.Assemblies which incorporate first and second microelectronic packagesmounted opposite one another on a circuit panel can have significantlyreduced stub lengths between the respective packages. Reducing the stublengths within such assemblies can improve electrical performance, suchas by reducing one or more of settling time, ringing, jitter, orintersymbol interference, among others. Moreover, it may be possible toobtain other benefits as well, such as simplifying the structure of thecircuit panel or reducing the complexity and cost of designing ormanufacturing the circuit panel, or for both designing and manufacturingthe circuit panel.

Certain embodiments of the invention provide a package ormicroelectronic assembly in which a microelectronic element, e.g., asemiconductor chip, or stacked arrangement of semiconductor chips, isconfigured to predominantly provide a memory storage array function. Insuch microelectronic element, the number of active devices, e.g.,transistors therein that are configured, i.e., constructed andinterconnected with other devices, to provide the memory storage arrayfunction, is greater than the number of active devices that areconfigured to provide any other function. Thus, in one example, amicroelectronic element such as a DRAM chip may have memory storagearray function as its primary or sole function. Alternatively, inanother example, such microelectronic element may have mixed use and mayincorporate active devices configured to provide memory storage arrayfunction, and may also incorporate other active devices configured toprovide another function such as processor function, or signal processoror graphics processor function, among others. In this case, themicroelectronic element may still have a greater number of activedevices configured to provide the memory storage array function than anyother function of the microelectronic element.

The microelectronic elements have faces with a plurality of columns ofelement contacts on the faces. In some embodiments, the microelectronicelements are each flip-chip mounted to the substrate, such that theelement contacts of the first and second microelectronic elements facerespective first and second sets of substrate contacts on a firstsurface of a substrate and are joined thereto. In other embodiments, amicroelectronic element may include a first semiconductor chip adjacentthe substrate and electrically connected thereto, and one or more secondsemiconductor chips overlying the first semiconductor chip andelectrically connected therewith that are configured to predominantlyprovide memory storage array function.

A plurality of terminals may be provided on the second surface of thesubstrate that are configured for connecting the microelectronic packagewith at least one component external to the package. The terminals thatare electrically connected with the substrate contacts include firstterminals which are arranged at positions within first and secondparallel grids.

In certain embodiments of the invention, the first and second grids areconfigured to carry all of a group of signals of a command-address busof the microelectronic element; i.e., command signals, address signals,bank address signals and clock signals that are transferred to themicroelectronic package, wherein the command signals include writeenable, row address strobe, and column address strobe signals, and theclock signals are clocks used for sampling the address signals. Whilethe clock signals can be of various types, in one embodiment, the clocksignals carried by these terminals can be one or more pairs ofdifferential clock signals received as differential or true andcomplement clock signals.

On a circuit panel, e.g., a printed circuit board, module card, etc.,these above-noted signals of the command-address bus: i.e., commandsignals, address signals, bank address signals and clock signals, can bebussed to multiple microelectronic packages that are connected theretoin parallel. Providing duplicate sets of first terminals in first andsecond parallel grids in which the signal assignments in one grid are amirror image of the signal assignments in the other grid can reduce thelengths of stubs in an assembly of first and second microelectronicpackages mounted opposite one another to a circuit panel.

When first and second microelectronic packages are mounted to oppositemounting surfaces of a circuit panel with the circuit panel electricallyinterconnecting the packages, each of the first terminals of the firstgrid of the first package can be aligned within a distance of one ballpitch of the corresponding first terminals of the second, mirror imagegrid of the second package to which they connect, i.e., thecorresponding grids can be aligned within a distance of one ball pitchof one another in orthogonal x and y directions parallel to one of themounting surfaces of the circuit panel, the ball pitch being no greaterthan a minimum pitch between any two adjacent parallel columns of theterminals on either package. In addition, each of the first terminals ofthe first grid of the second package can be so aligned within one ballpitch of the corresponding first terminals of the second, mirror imagegrid of the first package to which they connect. As a result, each firstterminal of the first package can be electrically connected with acorresponding first terminal of the second package, with the mountinglocations of each pair of terminals on the opposite circuit panelsurfaces being aligned within one ball pitch of each other in orthogonalx and y directions parallel to one of the surfaces of the circuit panel.

In some cases, the mounting locations of each pair of connectedterminals on the opposite circuit panel surfaces may even be coincidentwith one another. Accordingly, the lengths of the electrical connectionsthrough the circuit panel between pairs of electrically connected firstterminals of the first and second packages can be significantly reduced,in that the terminals in each of these pairs of electrically connectedfirst terminals may overlie one another, or at least be aligned withinone ball pitch of one another in x and y orthogonal directions along thefirst circuit panel surface.

The circuit panel construction may also be simplified in an assemblyhaving this construction because the routing between each electricallyconnected pair of first terminals can be mostly in a vertical direction,i.e., in a direction through the thickness of the circuit panel. Thatis, straight through via connections on the circuit panel may be allthat is needed to electrically connect each pair of corresponding firstterminals of the packages mounted to the opposite surfaces of thecircuit panel.

Moreover, it may be possible to reduce the number of routing layers ofwiring on the circuit panel required to route the signals from theabove-noted signals carried by the first terminals, e.g.,command-address bus signals, between connection sites where respectivepairs of microelectronic packages are connected. Specifically, thenumber of routing layers required to route such signals along thecircuit panel may in some cases be reduced to two or fewer routinglayers. However, on the circuit panel, there may be a greater number ofrouting layers that carry other signals than the number of routinglayers that carry the above-noted address or command-address bussignals.

The microelectronic package may also have second terminals other thanthe first terminals, such terminals typically being configured to carrysignals other than the above-noted address or command-address bussignals. In one example, the second terminals can include terminals usedfor carrying uni-directional or bi-directional data signals to and orfrom the microelectronic element, and data strobe signals, as well asdata masks and ODT or “on die termination” signals used to turn on oroff parallel terminations to termination resistors. Signals or referencepotentials such as chip select, reset, power supply voltages, e.g., Vdd,Vddq, and ground, e.g., Vss and Vssq, can be carried by the secondterminals; none of the signals or reference potentials needs to becarried by the first terminals. In some embodiments, it is possible forsome or all terminals configured to carry signals other than theabove-noted address or command-address bus signals to be disposed assecond terminals in whichever locations on the package they can beplaced.

Alternatively, in some embodiments it is possible for some or allterminals which are configured to carry signals other than the abovenoted address or command-address bus signals to be disposed in the firstgrid and the second, mirror image grid of terminals on the package. Inthis way, it may be possible to reduce the stub lengths in theelectrical connections provided on a circuit panel between correspondingterminals, as described above.

In other embodiments, some or all of the terminals which are configuredto carry signals other than the above-noted address or command-addressbus signals can be disposed as a set of second terminals in a third gridon the package surface, and another set of the second terminals in afourth grid on the same package surface, in which the signal assignmentsof the second terminals in the third grid are a mirror image of thesignal assignments of the second terminals in the fourth grid. In thisway, similar to the connections between corresponding first terminals offirst and second packages as described above, the lengths of theelectrical connections through the circuit panel between pairs ofelectrically connected second terminals of the first and second packagescan be significantly reduced. In an example, a pair of electricallyconnected second terminals may be aligned within one ball pitch of oneanother. In a particular example, the terminals in each of these pairsof electrically connected second terminals may overlie one another,i.e., be coincident with one another. Moreover, benefits similar tothose described above for reducing stub lengths and simplifying theconstruction of a circuit panel for the connections between the firstand second packages may be obtained when second terminals of amicroelectronic package are arranged in this way.

Thus, a microelectronic package 100 according to an embodiment of theinvention is illustrated in FIGS. 5, 6, and 7. As seen therein, thepackage 100 can include first and second microelectronic elements 101,103 each being configured to predominantly provide memory storage arrayfunction, in that each of the first and second microelectronic elementshas a greater number of active devices, e.g., transistors, configured toprovide memory storage array function than any other function, asindicated above.

The first and second microelectronic elements have element contacts 111,113 at their respective faces 105. In one type of such microelectronicelement 101, 103, each one of some contacts of the element contacts 111,113 is dedicated to receiving a respective address signal of theplurality of address signals supplied to the microelectronic element. Inthis case, each of such contacts 111, 113 is able to receive onerespective address signal of the plurality of address signals suppliedto the microelectronic element 101, 103 from the outside.

In one particular example of this type of microelectronic element 101,103, each of the plurality of address signals present at the elementcontacts 111, 113 can be sampled relative to an edge of a clock used bythe respective microelectronic element, i.e., upon on a transition ofthe clock between first and second different voltage states. That is,each address signal can be sampled upon a rising transition between alower voltage state and a higher voltage state of the clock, or upon afalling transition between a higher voltage state and a lower voltagestate of the clock. Thus, the plurality of address signals may all besampled upon the rising transition of the clock, or such address signalsmay all be sampled upon the falling transition of the clock, or inanother example, the address signal at one of the element contacts 111,113 can be sampled upon the rising transition of the clock and theaddress signal at one other external contact can be sampled upon thefalling transition of the clock.

In another type of microelectronic element 101, 103 configured topredominantly provide memory storage array function, one or more of theaddress contacts thereon can be used in a multiplexed manner. In thisexample, a particular element contact 111, 113 of the respectivemicroelectronic element 101, 103 can receive two or more differentsignals supplied to the microelectronic element from the outside. Thus,a first address signal can be sampled at the particular contact 111, 113upon a first transition of the clock between the first and seconddifferent voltage states (e.g., a rising transition), and a signal otherthan the first address signal can be sampled at the particular contactupon a second transition of the clock (e.g., a falling transition)between the first and second voltage states that is opposite the firsttransition.

In such a multiplexed manner, two different signals can be receivedwithin the same cycle of the clock on the same element contact 111, 113of the respective microelectronic element 101, 103. In a particularcase, multiplexing in this manner can allow a first address signal and adifferent signal to be received in the same clock cycle on the sameelement contact 111, 113 of the respective microelectronic element 101,103. In yet another example, multiplexing in this manner can allow afirst address signal and a second different address signal to bereceived in the same clock cycle on the same element contact 111, 113 ofthe respective microelectronic element 101, 103.

The substrate 102 can include a dielectric element 122, which in somecases can consist essentially of polymeric material, e.g., a resin orpolyimide, among others. Alternatively, the substrate can include adielectric element having a composite construction such asglass-reinforced epoxy, e.g., of BT resin or FR-4 construction. In someexamples, the dielectric element has a coefficient of thermal expansionin the plane of the dielectric element, i.e., in a direction parallel toa first surface 108 thereof, of up to 30 parts per million per degreeCelsius (hereinafter, “ppm/° C.”). In another example, the substrate caninclude a supporting element of material having a coefficient of thermalexpansion (“CTE”) of less than 12 parts per million per degree Celsius,on which the terminals and other conductive structure are disposed. Forexample, such low CTE element can consist essentially of glass, ceramicor semiconductor material or liquid crystal polymer material, or acombination of such materials.

As seen in FIG. 6, a first set 121 and a second set 123 of substratecontacts are disposed at a first surface 108 of the substrate, the firstset 121 of substrate contacts facing the element contacts 111 of thefirst microelectronic element and being joined thereto at 138, such aswith a bond metal, e.g., solder, tin, indium, eutectic, or gold, amongothers, or other conductive bond material, or possibly other structuresuch as a conductive bump or a micropillar, among possible structures.In some cases, a die attach adhesive or underfill may be disposedbetween the faces 105 of the microelectronic elements and the surface108 of the substrate 102, which may mechanically reinforce theconnection between the microelectronic elements and the substrate, andmay mechanically support the joints between the microelectronic elementsand the substrate.

The second set 123 of the substrate contacts face the element contacts113 of the second microelectronic element and are joined thereto. In theembodiment as particularly shown in FIG. 6, the faces 105 of the firstand second microelectronic elements 101, 103, can be arranged in asingle plane 112 that is parallel to the first surface 108 of thesubstrate 102.

As particularly shown in FIG. 5, in some embodiments, the contacts ofeach microelectronic element may be arranged in a single column as shownfor contacts 111, or the contacts may be arranged in a plurality ofcolumns as shown for contacts 113. Each column may contain a contact ateach vertical layout position of the column along direction 134, or acontact may be missing from one or more positions of a column, as in thecase of one of the columns of contacts 113. In a particular embodiment,the contacts may be arranged in an area array over the face 105 of themicroelectronic element. In another example, the contacts of amicroelectronic element can be arranged in one or more sets of contactsadjacent one or more peripheral edges of the microelectronic elementindicated by the dashed lines marking the boundaries of themicroelectronic elements 101, 103 in FIG. 5. In a particular example,the microelectronic element can be a single semiconductor chip and thecontacts 111, or 113 thereon may be “chip contacts” which are thecontacts of the semiconductor chip. In another example, a particularmicroelectronic element can include one or more semiconductor chips eachhaving chip contacts, and the contacts 111, or 113 may includeredistribution contacts which are formed on a face 105 thereof, andwhich are electrically connected to the chip contacts by conductiveelements such as traces and vias, for example. An example of such amicroelectronic element is described below with reference to FIG. 26D.Unless otherwise noted, the “contacts” of the microelectronic elementsin each of the examples herein can be arranged in any of these describedways.

The microelectronic element 101, or microelectronic element 103 or bothmay also include additional contacts that may not be disposed within acolumn of the element contacts. These additional contacts may be usedfor connection to power, ground, or as contacts available for contactwith a probing device, such as may be used for testing.

As seen in FIG. 5, the package 100 can have first terminals 104 andsecond terminals 106 for electrically and mechanically connecting thepackage 100 with a component external to the package 100, such as acircuit panel, for example. The terminals 104, 106 can be electricallyconductive pads, posts, or other electrically conductive structure. Inthe example seen in FIG. 6, the terminals in some cases may includejoining elements 130, such as may include a bond metal such as solder,tin, indium, gold, or a eutectic material, among others, or otherconductive bond material, and may in some cases also include additionalstructure such as a conductive bump attached to conductive structure ofthe substrate such as conductive pads or posts. The first terminals 104and the second terminals 106 can be electrically connected with thesubstrate contacts 121, 123 through electrically conductive structure onthe substrate, such as traces and vias, for example.

A first set of the first terminals 104 can be arranged at positionswithin a first grid 114 at a second surface 110 of the substrate 102opposite from the first surface 108. A second set of the first terminals104 can be arranged at positions within a second grid 124 at the secondsurface 110 of the substrate. Although, in some of the figures, thefirst and second grids are shown extending beyond the outer boundariesof the front surface of the microelectronic elements, that need not bethe case. In certain embodiments of the invention, each of the first andsecond grids 114, 124 of first terminals can be configured to carrycertain signals of the command-address bus, that is, specifically all ofa set of address signals of microelectronic elements 101, 103 configuredto provide dynamic memory storage function in a microelectronic package100.

For example, when the microelectronic elements 101, 103 include or areDRAM semiconductor chips, each of the first and second grids 114, 124are configured to carry sufficient address information transferred tothe microelectronic package 100 that is usable by circuitry within thepackage, e.g., row address and column address decoders, and bankselection circuitry, if present, to determine an addressable memorylocation from among all the available addressable memory locations of amemory storage array within a microelectronic element in the package. Ina particular embodiment, each of the first and second grids 114, 124 canbe configured to carry all the address information used by suchcircuitry within the microelectronic package 100 to determine anaddressable memory location within such memory storage array.

In a variation of such embodiment, each of the first and second grids114, 124 can be configured to carry a majority of the addressinformation that is used by such circuitry within the microelectronicpackage 100 to determine an addressable memory location within suchmemory storage array, and then other terminals such as at least some ofthe above-referenced second terminals 106 on the microelectronic packagewould then be configured to carry the remaining part of the addressinformation. In such variation, in a particular embodiment, each of thefirst and second grids 114, 124 are configured to carry three-quartersor more of the address information that is used by such circuitry withinthe microelectronic package 100 to determine an addressable memorylocation within such memory storage array.

In a particular embodiment, each of the first and second grids 114, 124may not be configured to carry chip select information, e.g.,information usable to select a particular chip within themicroelectronic package 100 for access to a memory storage locationwithin the chip. In another embodiment, at least one of the first andsecond grids 114, 124 may indeed carry chip select information.

Typically, when the microelectronic elements 101, 103 in themicroelectronic package 100 include DRAM chips, the address signals inone embodiment can include all address signals that are transferred tothe package from a component external to the package, e.g., a circuitpanel such as the circuit panel 154 described below, which are used fordetermining a random access addressable memory location within themicroelectronic package for read access thereto, or for either read orwrite access thereto.

At least some of the second terminals 106 can be configured to carrysignals other than the address signals that are carried by the firstterminals 104 of the first and second grids 114, 124. Signals orreference potentials such as chip select, reset, power supply voltages,e.g., Vdd, Vddq, and ground, e.g., Vss and Vssq, can be carried by thesecond terminals 106; none of these signals or reference potentialsneeds to be carried by the first terminals 104 in any of the embodimentsreferred to herein, unless otherwise noted.

In a particular embodiment, each of the first and second grids 114, 124of each microelectronic package can be configured to carry informationthat controls an operating mode of at least one of the first and secondmicroelectronic elements 101, 103. More specifically, each of the firstand second grids 114, 124 can be configured to carry all of a particularset of command signals and/or clock signals transferred to themicroelectronic package 100. In such an embodiment, the first terminals104 can be configured to carry all of the command signals, addresssignals, bank address signals, and clock signals transferred to themicroelectronic package 100 from an external component, wherein thecommand signals include row address strobe, column address strobe andwrite enable. In such an embodiment, a first chip in a microelectronicelement having a composite structure, such as one of the microelectronicelements 901 shown in FIG. 21, for example, can be configured toregenerate the information that controls the operating mode.Alternatively, or in addition thereto, the first chip in such acomposite microelectronic element can be configured to partially orfully decode the information that controls the operating mode of themicroelectronic element. In such embodiment, each second chip may or maynot be configured to fully decode one or more of address information,command information, or information that controls an operating mode ofthe microelectronic element.

In an embodiment in which one or more of the microelectronic elementsare configured to provide dynamic memory storage array function, such asprovided by a dynamic random access memory (“DRAM”) semiconductor chip,or an assembly of DRAM chips, the command signals are write enable, rowaddress strobe, and column address strobe signals. Other signals such asODT (on die termination), chip select, clock enable, are not part of thecommand signals that need to be carried by the first and second grids114, 124. The clock signals can be clocks used by one or more of themicroelectronic elements for sampling the address signals. For example,as seen in FIG. 7, the first terminals 104 can include clock signals CKand CKB, row address strobe RAS, column address strobe CAS and writeenable signals WE, as well as address signals A0 through A15 inclusive,and bank address signals BA0, BA1 and BA2.

In this embodiment, at least some of the second terminals 106 can beconfigured to carry signals other than the command signals, addresssignals, and clock signals that are carried by the first terminals 104of the first and second grids 114, 124. Signals or reference potentialssuch as chip select, reset, power supply voltages, e.g., Vdd, Vddq, andground, e.g., Vss and Vssq, can be carried by the second terminals 106;none of these signals or reference potentials needs to be carried by thefirst terminals 106 in any of the embodiments referred to herein, unlessotherwise noted.

In another embodiment, when one or more of the microelectronic elementsare configured to provide memory storage array function implemented in atechnology other than for DRAM, such as NAND flash memory, for example,the particular command signals which need to be carried by the first andsecond grids 114, 124 can be a different set of signals other than thegroup of write enable, address strobe, and column address strobe signalswhich need to be carried in the DRAM case.

In one embodiment, at least some of the second terminals 106 that areconfigured to carry signals other than the address signals can bearranged at positions within the first and second grids 114, 124. In oneexample, at least some of the second terminals 106 that are configuredto carry signals other than the command signals, address signals, andclock signals can be arranged at positions within the first and secondgrids 114, 124. Although particular configurations of second terminals106 are shown in the figures, the particular configurations shown arefor illustrative purposes and are not meant to be limiting. For example,the second terminals 106 can also include terminals that are configuredto be connected to power or ground signals.

An arrangement of the first terminals in the first and second grids 114,124 of the package is particularly shown in FIGS. 5-7. In one example,each grid 114, 124 may include first and second parallel columns 136 ofterminals. The parallel columns 136 of terminals in each grid can beadjacent to one other. Alternatively, although not shown in FIGS. 5-7,at least one terminal may be disposed between the first and secondcolumns of terminals. In another example, such as seen in FIG. 5A, thegrids may include a column of terminals for which a column axis 119extends through a majority of the terminals 104 of such column, i.e., iscentered relative thereto. However, in such column, one or more of theterminals might not be centered relative to the column axis 119, as inthe case of terminals 104′. In this case, these one or more terminalsare considered part of a particular column, even though such terminal(s)might not be centered relative to axis 119 because they are closer tothe axis 119 of that particular column than to the axis of any othercolumn. The column axis 119 may extend through these one or moreterminals which are not centered relative to the column axis, or, insome cases, the non-centered terminals may be farther from the columnaxis such that the column axis 119 may not even pass through thesenon-centered terminals of the column. There may be one, several or manyterminals in one column or even in more than one column which are notcentered with respect to a column axis of the respective column in agrid.

Moreover, it is possible for the grids of terminals to containarrangements of terminals in groupings other than columns, such as inarrangements shaped like rings, polygons or even scattered distributionsof terminals. As shown in FIG. 6, an encapsulant 146 may overlie thefirst surface 108 of the substrate and may contact the microelectronicelements 101, 103 therein. In some cases, the encapsulant may overliesurfaces 145 of the microelectronic elements which face away from thesubstrate 102.

As seen in FIG. 7, the signal assignments of the first terminals in thesecond grid 124 are a mirror image of the signal assignments 124 of thefirst terminals in the first grid 114. Stated another way, the signalassignments of the first terminals in the first and second grids aresymmetric about an axis 132 between the first and second grids 114, 124,the axis 132 in this case extending in a direction 134 in which columns136 of the first terminals extend. With the signal assignments in thesecond grid 124 being a mirror image of those in the first grid 114, afirst terminal 104 of the first grid 114 which is assigned to carry thesignal CK (clock) is in the same relative vertical position (indirection 134) within the grid as the corresponding first terminal 104of the second grid 114 which is assigned to carry the signal CK.However, since the first grid 114 contains two columns 136 and theterminal of the first grid 114 assigned to carry the signal CK is in theleft column among the two columns 136 of the first grid, the mirrorimage arrangement requires that the corresponding terminal of the secondgrid 124 assigned to carry the signal CK is in the right column 136among the two columns of the second grid.

Another result of this arrangement is that the terminal assigned tocarry the signal WE (write enable) is also in the same relative verticalposition within the grid in each of the first and second grids 114, 124.However, in the first grid 114, the terminal assigned to carry WE is inthe right column among the two columns 136 of the first grid, and themirror image arrangement requires that the corresponding terminal of thesecond grid 124 assigned to carry the signal WE is in the left column136 among the two columns of the second grid 124. As can be seen in FIG.7, the same relationship applies for each first terminal in each of thefirst and second grids, at least for each first terminal assigned tocarry a command-address bus signal as discussed above.

The axis 132 about which the signal assignments of the first terminalsare symmetric can be located at various positions on the substrate. In aparticular embodiment, the axis can be a central axis of the packagethat is located equidistant from first and second opposed edges 140, 142of the substrate particularly when the columns 136 of the firstterminals extend in a direction parallel to the edges 140, 142 and thefirst and second grids are disposed at locations which are symmetricabout this central axis.

Alternatively, this axis of symmetry 132 can be offset in a horizontaldirection 135 from the central axis that is equidistant between edges140, 142. In one example, the axis 132 can be offset from a central axisor line that is parallel to and equidistant from the first and secondedges 140, 142 of the substrate 102, the offset distance being not morethan a distance of three and one-half times a minimum pitch between anytwo adjacent columns of the first terminals 104. In a particularembodiment, at least one column of terminals of each of the first andsecond grids 114, 124 can be disposed within an offset distance from acentral axis or line that is parallel to and equidistant from the firstand second edges 140, 142 of the substrate 102, the offset distancebeing a distance of three and one-half times a minimum pitch between anytwo adjacent columns of the first terminals 104.

In a particular example, the first terminals 104 of the first grid 114can be electrically connected with the first microelectronic element101, and the first terminals 104 of the second grid 124 can beelectrically connected with the second microelectronic element 103. Insuch case, the first terminals 104 of the first grid 114 may also be notelectrically connected with the second microelectronic element 103, andthe first terminals 104 of the second grid 124 of the package 100 mayalso be not electrically connected with the first microelectronicelement 101. In yet another example, the first terminals 104 of each ofthe first and second grids 114 can be electrically connected with eachof the first and second microelectronic elements 101, 103.

As mentioned above, the second terminals 106 can be configured to carrysignals other than the above-noted signals of the command-address bus.In one example, the second terminals 106 can include terminals used forcarrying uni-directional or bi-directional data signals to and or fromthe microelectronic element, and data strobe signals, as well as datamasks and ODT or “on die termination” signals used to turn on or offparallel terminations to termination resistors. Signals such as chipselect, reset, clock enable, as well as reference potentials such aspower supply voltages, e.g., Vdd, Vddq, or ground, e.g., Vss and Vssq,can be carried by the second terminals 106; none of the signals orreference potentials needs to be carried by the first terminals 104. Insome embodiments it is possible for some or all terminals that areconfigured to carry signals other than the command-address bus signalsto be disposed as second terminals 106 on the package, wherever they canbe suitably placed. For example, some or all of the second terminals 106can be arranged in the same grids 114, 124 on the substrate 102 in whichthe first terminals 104 are arranged. Some or all of the secondterminals 106 may be disposed in the same column or in different columnsas some or all of the first terminals 104. In some cases, one or moresecond terminals can be interspersed with the first terminals in thesame grids or column thereof.

In a particular example, some or all of the second terminals 106 can bedisposed in a third grid 116 on the second surface 110 of the substrate,and another set of the second terminals can be disposed in a fourth grid126 on the package surface 110. In a particular case, the signalassignments of the second terminals in the third grid 116 can be amirror image of the signal assignments of the second terminals in thefourth grid 126, in like manner to that described above for the firstand second grids. The third and fourth grids 116, 126 may in some casesextend in the direction 134 in which the first and second grids extendand can be parallel to one another. The third and fourth grids may alsobe parallel to the first and second grids 114, 124. Alternatively, eachof the third and fourth grids 116, 126 can extend in another direction135 which is transverse to or even orthogonal to direction 134.

In one example, second surface 110 of the substrate 102 can have firstand second peripheral regions adjacent to the first and second edges140, 142, respectively, wherein a central region separates the first andsecond peripheral regions. In such example, the first and second grids114, 124 can be disposed in the central region of the second surface110, and the third and fourth grids 116, 126 can be disposed in therespective first and second peripheral regions.

FIG. 8A illustrates an assembly 200 of first and second microelectronicpackages 100A, 100B, each being a microelectronic package 100 asdescribed with reference to FIGS. 5-7 above, as mounted to oppositefirst and second surfaces 150, 152 of a circuit panel 154. The circuitpanel can be of various types, such as a printed circuit board used in adual-inline memory module (“DIMM”) module, a circuit board or panel tobe connected with other components in a system, or a motherboard, amongothers. The first and second microelectronic packages 100A, 100B can bemounted to corresponding contacts 160, 162 exposed at the first andsecond surfaces 150, 152 of the circuit panel 154.

As particularly shown in FIG. 8A, because the signal assignments of thefirst terminals in the second grid 124 of each package are a mirrorimage of the signal assignments of the first terminals in the first grid114 of each package, when the packages 100A, 100B are mounted to thecircuit panel opposite one another, each first terminal in the firstgrid 114A of the first package 100A is aligned with the correspondingfirst terminal in the second grid 124B of the second package 100B whichhas the same signal assignment and to which it is electricallyconnected. Moreover, each first terminal in the second grid 124A of thefirst package 100A is aligned with the corresponding first terminal inthe first grid 114B which has the same signal assignment and to which itis electrically connected.

To be sure, the alignment of each pair of connected terminals can bewithin a tolerance, such that each pair of connected terminals can bealigned within one ball pitch of one another in orthogonal x and ydirections along the first surface 150 of the circuit panel 154.Alternatively, connected terminals on opposite surfaces of the circuitpanel can be coincident with one another. In a particular example, amajority of the positions of the aligned grids of the respective firstand second packages 100A, 100B (e.g., the first grid 114A of the firstpackage and the second grid 124B of the second package) can be alignedwith one another in orthogonal x and y directions along the firstsurface 150 of the circuit panel 154.

Thus, as further shown in FIG. 8A, a particular first terminal thatcarries a signal marked “A” in grid 114A of the first package 100A isaligned with the corresponding first terminal of grid 124B of the secondpackage 100B that carries the same signal “A”. The same is also trueregarding a particular first terminal that carries a signal marked “A”in grid 124A of the first package 100A that is aligned with thecorresponding first terminal of grid 114B of the second package 100Bthat carries the same signal “A”.

In this way, as further seen in FIG. 8A, the lengths of the electricalconnections through the circuit panel between each pair of electricallyconnected first terminals of the first and second packages 100A, 100Bcan be significantly reduced, in that the terminals in each of thesepairs of electrically connected second terminals may overlie oneanother, or at least be aligned within one ball pitch of one another.The reductions in the lengths of these electrical connections can reducestub lengths in the circuit panel and the assembly, which can helpimprove the electrical performance, such as reducing settling time,ringing, jitter, or intersymbol interference, among others, for theabove-noted signals which are carried by the first terminals and whichare transferred to microelectronic elements in both the first and secondpackages. Moreover, it may be possible to obtain other benefits as well,such as simplifying the structure of the circuit panel or reducing thecomplexity and cost of designing or manufacturing the circuit panel.

Therefore, referring to FIG. 8D, the electrical lengths of stubs on thecircuit panel 354 which electrically connect a first terminal 104A ofthe first package 100A with the corresponding first terminal 104A on thesecond package 100B can be less than seven times a minimum pitch of thefirst terminals on each package, for example, less than seven times thepitch 151 between columns 104A, 104B of first terminals in FIG. 5.Stated another way, referring to FIG. 8A, the total combined length ofthe conductive elements connecting a pair of electrically coupled firstand second panel contacts 160, 162 exposed at the first and secondsurfaces of the circuit panel 150, 152 for electrically interconnectingthe first and second panel contacts with one of the command signals,address signals, bank address signals or clock signals can be less thanseven times a smallest pitch of the panel contacts.

As further shown in FIG. 8B, when the second terminals of each package100A, 100B are arranged in third and fourth grids having the specificmirror image arrangement described above with respect to FIGS. 5-7, eachsecond terminal of each package's third grid can be aligned with thecorresponding second terminal of the other package's fourth grid whichhas the same signal assignment and to which it is electricallyconnected. Thus, as seen in FIG. 8B, each second terminal in the thirdgrid 116A of the first package 100A is aligned with the correspondingfirst terminal in the fourth grid 126B of the second package 100B whichhas the same signal assignment and to which it is electricallyconnected. Moreover, each first terminal in the fourth grid 126A of thefirst package 100A is aligned with the corresponding first terminal inthe third grid 116B which has the same signal assignment and to which itis electrically connected. Again, the alignment of each pair ofconnected terminals is within a tolerance, such that each pair ofconnected terminals can be aligned within one ball pitch of one anotherin orthogonal x and y directions along the first surface 150 of thecircuit panel 154.

Thus, as further shown in FIG. 8B, a particular first terminal thatcarries a signal marked “B” in grid 116A of the first package 100A isaligned with the corresponding first terminal of grid 126B of the secondpackage 100B that carries the same signal “B” and to which it iselectrically connected. The same is also true regarding a particularfirst terminal that carries a signal marked “B” in grid 126A of thefirst package 100A that is aligned with the corresponding first terminalof grid 116B of the second package 100B that carries the same signal “B”and to which it is electrically connected.

Similar to the connections between corresponding first terminals 104 offirst and second packages as described above, in this embodiment, thelengths of the electrical connections through the circuit panel betweenpairs of electrically connected second terminals 106 of the first andsecond packages can be significantly reduced, in that the terminals ineach of these pairs of electrically connected second terminals may becoincident with one another, or at least be aligned within one ballpitch of one another in orthogonal x and y directions parallel to thecircuit panel surface. As used herein, when grids of terminals ofpackages at opposite surfaces of a circuit panel are “coincident” withone another, the alignment can be within customary manufacturingtolerances or can be within a tolerance of less than one-half of oneball pitch of one another in x and y orthogonal directions parallel tothe first and second circuit panel surfaces, the ball pitch being asdescribed above.

Moreover, benefits similar to those described above for reducing stublengths and simplifying the construction of a circuit panel for theconnections between the first and second packages may be obtained whenthe second terminals of a microelectronic package are arranged in thisway, i.e., terminals which can be assigned to carry signals other thanthe above-noted signals of the command-address bus.

FIG. 8C further illustrates that two, or more pairs of microelectronicpackages each having a construction either as described above orhereinafter can be electrically interconnected with respective panelcontacts on a circuit panel 154, e.g., a board of a dual-inline memorymodule (“DIMM”), in similar orientations as packages 100A, 100B. Thus,FIG. 8C shows an additional pair of packages 100C, 100D electricallyinterconnected with circuit panel 154 in opposite orientations facingone another as described above. In addition to packages 100A, 100B,100C, and 100D one or more other pairs of packages may also beelectrically interconnected with circuit panel, such as described above.

FIG. 8D illustrates a microelectronic assembly such as, for example, aDIMM, among others, incorporating a circuit panel and a plurality ofmicroelectronic packages mounted opposite one another to first andsecond opposite surfaces thereof. As seen in FIG. 8D, the above-notedaddress signals or command-address bus signals can be routed on a bus36, e.g., an address bus or command-address bus on the circuit panel orcircuit board 354, in at least one direction 143 between connectionsites I, II or III at which respective pairs of microelectronic packages100A, 110B are connected to opposite sides of the circuit panel. Signalsof such bus 36 reach each pair of packages at the respective connectionsites I, II or III at slightly different times. The at least onedirection 143 can be transverse or orthogonal to a direction 142 inwhich at least one column 138 of a plurality of contacts on at least onemicroelectronic element within each package 100A or 100B extends. Insuch way, the signal conductors of the bus 36 on (i.e., on or within)the circuit panel 354 can in some cases be spaced apart from one anotherin a direction 142 which is parallel to the at least one column 138 ofcontacts on a microelectronic element within a package 100A, or 100Bconnected to the circuit panel.

Such a configuration, particularly when the first terminals 104A, 104Bof each microelectronic package are arranged in one or more columnsextending in such direction 142, may help simplify the routing of signalconductors of one or more global routing layers on the circuit panelused to route the signals of the bus 36. For example, it may be possibleto simplify routing of the command-address bus signals on a circuitpanel when relatively few first terminals are disposed at the samevertical layout position on each package. Thus, in the example shown inFIG. 7, only four first terminals are disposed at the same verticallayout position on each package, such as the first terminals in eachgrid 114, 124 configured to receive address signals A3 and A1.

In one embodiment, the microelectronic assembly 354 can have amicroelectronic element 358 that can include a semiconductor chipconfigured to perform buffering of at least some signals transferred tothe microelectronic packages 100A, 100B of the assembly 354. Such amicroelectronic element 358 having a buffering function can beconfigured to help provide impedance isolation for each of themicroelectronic elements in the microelectronic packages 100A and 100Bwith respect to components external to the microelectronic assembly 354.

In an exemplary embodiment, the microelectronic assembly 354 can have amicroelectronic element 358 that can include a semiconductor chipconfigured predominantly to perform a logic function, such as a solidstate drive controller, and one or more of the microelectronic elementsin the microelectronic packages 100A and 100B can each include memorystorage elements such as nonvolatile flash memory. The microelectronicelement 358 can include a special purpose processor that is configuredto relieve a central processing unit of a system such as the system 1200(FIG. 28) from supervision of transfers of data to and from the memorystorage elements included in the microelectronic elements. Such amicroelectronic element 354 including a solid state drive controller canprovide direct memory access to and from a data bus on a motherboard(e.g., the circuit panel 1202 shown in FIG. 28) of a system such as thesystem 1200.

In such an embodiment of the microelectronic assembly 354 having amicroelectronic element 358 that includes a controller function and/or abuffering function, the command-address bus signals can be routedbetween the microelectronic element 358 and each pair of packages 100Aand 100B at respective connection sites I, II or III. In the particularexample shown in FIG. 8D, a portion of the command-address bus 36 thatextends past the connection sites I, II or III can extend in thedirection 143 or in another direction transverse to the direction 143 toreach contacts of the microelectronic element 358. In one embodiment,the command-address bus 36 can extend in the direction 143 to reachcontacts of the microelectronic element 358.

FIG. 9 illustrates a particular arrangement of terminals withinrespective first grids 214, 224, and second grids 216, 226 of thepackage 250, illustrating that terminals at the same relative verticalposition within adjacent columns 236, 238 in each grid may in fact bedisposed at positions which are somewhat offset in the vertical layoutdirection 134 of the package.

FIG. 10 illustrates a particular arrangement of first terminals in firstand second parallel grids 244, 254, each of which can include threeadjacent columns of terminals. As shown in FIG. 10, the columns mayoverlie portions of the faces of the microelectronic elements where theelement contacts 111, 113 are disposed. As mentioned above, in someembodiments, it may be possible for signals other than the above-notedcommand-address bus signals to also be assigned to terminals within thesame grids which carry the particular command-address bus signals. FIG.10 illustrates one possible arrangement thereof.

In a further embodiment (not shown) which is a variation of theembodiment shown and described above relative to FIGS. 5-7, it ispossible for the first terminals arranged to carry the above-notedcommand-address bus signals to be provided in first and secondindividual columns of terminals, wherein each respective individualcolumn contains a set of first terminals configured to carry all of theabove-noted command address bus signals. The first terminals can furtherbe arranged such that the signal assignments in the first column are amirror image of the signal assignments in the second column, in that thesignal assignments are symmetric about an axis extending in the samedirection as the first and second columns and between the individualcolumns. In this way, the signal assignments of the first terminals inthe first column are the same as the signal assignments of the firstterminals at the same relative vertical positions in the second columnon the package.

FIG. 11 illustrates a variation of the above embodiment in which apackage 300 which can be similar in all respects with the packagedescribed above relative to FIGS. 5-7, except that the package 300 canbe implemented as a wafer-level package having a dielectric layer 302formed on the faces 105 of the microelectronic elements 101, 103.Metalized vias 308 are formed, e.g., by plating or depositing a metal orconductive material such as a conductive paste, conductive matrixmaterial, etc. in contact with the element contacts 111, 113 of eachmicroelectronic element. The vias 308 may be formed integrally withelectrically conductive traces 309 extending in a direction parallel toa surface 310 of the dielectric layer 302. The vias and some or all ofthe conductive traces of the package may be integral parts of amonolithic metal layer. In a particular examples, one metal layer ormore than one such metal layer can be formed by a build-up process ofplating, printing, dispensing, screen printing, stenciling or otherappropriate technique after forming dielectric layer 302 on themicroelectronic elements. The structure of the wafer-level package 300and the techniques for making it can be applied to any of the otherembodiments shown or described in this application.

FIG. 12 illustrates an assembly of first and second packages 400A, 400Bin which the first and second grids 414, 424 within each package are nowdisposed at locations close to the element contacts 111, 113 of eachmicroelectronic element 101, 103. The locations of second terminals,which may or may not be disposed in third and fourth grids as describedabove, are omitted from FIG. 12 for clarity, as is the case in figuresdepicting other embodiments described below. In this case, nearness ofthe first terminals in the grids 414, 424 with the element contacts mayalso help to reduce the lengths of stubs within each package 400A, 400B.Various ways of reducing the stub lengths within packages in which thepackage terminals are disposed in a central region proximate the elementcontacts of microelectronic elements therein are described inApplicants' co-pending U.S. Provisional Application No. 61/542,488(Attorney Docket No. TIPI 3.8-688) of Richard D. Crisp, Belgacem Habaand Wael Zohni entitled “Stub Minimization for Assemblies without Wirebonds to Package Substrate” filed Oct. 3, 2011, the disclosure of whichis incorporated by reference herein.

FIGS. 13-14 illustrate a microelectronic package 500 according to avariation of the above-described embodiment of FIGS. 5-7 in which first,second, third and fourth microelectronic elements 501, 503, 505 and 507are incorporated therein. The package further depicts four grids 514,524, 534, 544 of first terminals assigned to carry the above-notedsignals of the command-address bus. The second terminals, which areshown in FIG. 14 as grids 516, 526, 536, and 546, are omitted from FIG.13 for clarity. As in the above-described example, each grid of firstterminals can be electrically connected with just one of themicroelectronic elements, or can be connected to two or more of themicroelectronic elements. FIG. 14 illustrates one possible arrangementof the package 500 showing the grids 514, 524, 534, and 544 of firstterminals and one possible arrangement of grids 516, 526, 536, and 546of second terminals.

As shown in FIG. 14, each of the microelectronic elements typically hastwo first parallel edges 510, which may extend in the same direction ora different direction in which the one or more columns of contacts onthe microelectronic element extend. In one example, these first edgesmay each be longer than two second parallel edges 512 of eachmicroelectronic element. In another example, these first edges 510 maymerely extend in the same direction as the one or more columns ofcontacts, while in fact being shorter than the second edges 512 of thesame microelectronic element. References to the first and second edgesof microelectronic elements in each of the packages described belowincorporate these definitions.

As further seen in FIGS. 13 and 14, in this particular variation, two ofthe grids 524, 534 of first terminals can be disposed close to acenterline 530 of the package separating microelectronic elements 503,505, while the other grids 514, 544 of first terminals can be disposednear peripheral edges 550, 552 of the package. In the embodiment shownin FIGS. 13 and 14, there are no terminals separating the grids 524 and534 of first terminals from one another.

As will be appreciated, it is possible to provide a package (not shown)containing only three of the above-described microelectronic elements501, 503, 505, 507 and containing an appropriate number of grids offirst terminals, and grids of second terminals for connecting thepackage to a component external to the package, such as a circuit panel.

FIG. 15 is a plan view illustrating a package 560 according to avariation of that shown in FIG. 14, in which the positions of the gridsof the first terminals on the package are varied. In this case, viewingthe differences between package 560 and package 500 of FIG. 14, theposition of the grid 534 within package 560 is exchanged with theposition of the grid 536 of second terminals, such that the grid 536 isnow disposed between the grids 524, 534 of the first terminals. Inaddition, the position of the grid 544 within the package 560 isexchanged with the position of the grid 546 of second terminals, suchthat the grid 546 is now disposed between the grids 534, 544 of thefirst terminals.

FIG. 16 is a plan view illustrating a package 570 according to anothervariation of that shown in FIG. 14, in which the positions of the gridsof the first terminals are varied. In this case, viewing the differencesbetween package 570 and package 500 of FIG. 14, the position of the grid524 of first terminals within the package 570 is exchanged with theposition of the grid 526 of second terminals, such that the grid 524 isnow disposed between and adjacent to grids 514, 526. In addition, theposition of the grid 534 within the package 570 is exchanged with theposition of the grid 536 of second terminals, such that the grid 534 isnow disposed between and adjacent to grids 536, 544.

FIG. 17 is a plan view illustrating a package 600 according to a furthervariation of the above-described embodiment of FIGS. 5-7 in which first,second, third and fourth microelectronic elements 601, 603, 605, 607 arearranged in a matrix on the substrate, wherein each microelectronicelement has first edges 610 which typically are parallel and extend in afirst direction along the substrate, and second edges 612 whichtypically are parallel and extend in a second direction along thesubstrate. As seen in FIG. 17, the microelectronic elements can bearranged with the first edges 610 of microelectronic elements 601, 603adjacent and parallel to one another, and the first edges ofmicroelectronic elements 605, 607 adjacent and parallel to one another,as well. The microelectronic elements may be arranged such that onesecond edge 612 of microelectronic element 601 is adjacent and parallelto the second edge 612 of the other microelectronic element 607, and onesecond edge 612 of microelectronic element 603 is adjacent and parallelto one second edge 612 of the other microelectronic element 605. Each ofthe first edges 610 of microelectronic element 601 can in some cases becollinear with the first edges 610 of microelectronic element 607.Likewise, each of the first edges 610 of microelectronic element 603 canin some cases be collinear with the first edges 610 of microelectronicelement 605.

Grids 651, 653, 655, 657 of second terminals, which may overlie portionsof respective microelectronic elements 601, 603, 605, 607 and areelectrically connected therewith, can have terminals disposed in anysuitable arrangement, there being no requirement to place these secondterminals in grids in which the signal assignments in any one of thegrids 651, 653, 655, or 657 are a mirror image of the signal assignmentsof the terminals in any one of the other grids 651, 653, 655, or 657.

In a particular example, the signal assignments of the second terminalsin any one of the grids 651, 653, 655, or 657 can be a mirror image ofthe signal assignments of the second terminals in one or two other onesof the grids 651, 653, 655, or 657, in that the signal assignments ofany one of the grids can be symmetric about a vertical axis 680 withrespect to the signal assignments of another grid, and/or the signalassignments of any one of the grids can be symmetric about a horizontalaxis 682 with respect to the signal assignments of another grid.

For example, as shown in FIG. 17, the signal assignments of the thirdgrid 651 are symmetric about the vertical axis 680 with respect to thesignal assignments of the fourth grid 653, where the vertical axis 680extends in a direction 620 which in the example shown is between thegrids 651 and 653. Also, the signal assignments of the third grid 651are symmetric about the horizontal axis 682 with respect to the signalassignments of the sixth grid 657, where the horizontal axis 682 extendsin a direction 622, which in the example shown is between the grids 651and 657. In an alternative arrangement, each of the grids 651 and 657may extend to portions of the substrate surface on both sides of thehorizontal axis 682, and the relationships described above can otherwisebe present.

In the particular example shown in FIG. 17, the signal assignments ofthe first and fourth grids 651 and 657 are symmetric about the verticalaxis 680 with respect to the signal assignments of the respective secondand third grids 653 and 655. Also, the signal assignments of the firstand second grids 651 and 653 are symmetric about the horizontal axiswith respect to the signal assignments of the respective fourth andthird grids 657 and 655.

FIG. 18 is a plan view illustrating a microelectronic package 700according to another variation of the above-described embodiment (FIGS.13-14), in which the first edges 710 of first and second microelectronicelements 701, 703 extend in a first direction 720 parallel to the edge702 of terminal-bearing substrate surface 704, and where the secondedges 712 of microelectronic elements 701, 703 extend in a seconddirection 722 parallel to the terminal-bearing surface 704 of thesubstrate. The package 700 further includes third and fourthmicroelectronic elements 705, 707. However, the first edges 730 of thethird and fourth microelectronic elements 705, 707 extend in the seconddirection 722, and the second edges 732 of the third and fourthmicroelectronic elements 705, 707 extend in the first direction 720.

As further seen in FIG. 18, in one example, first and second grids 714,724 of first terminals configured to carry the above-notedcommand-address bus signals, can be provided in locations on thesubstrate surface away from the substrate's peripheral edges 740. Thesignal assignments of the first terminals in the second grid 724 can bea mirror image of the signal assignments of the first terminals in thefirst grid, as described above. In one example as shown in FIG. 18, thefirst and second grids 714, 724 of first terminals may be disposedbetween adjacent first edges 710 of the first and second microelectronicelements 701, 703 and may overlie portions of the third and fourthmicroelectronic elements 705, 707. Grids of second terminals 751, 753,755, 757 may at least partially overlie respective microelectronicelements 701, 703, 705, 707 to which the second terminals thereinelectrically connect.

As seen in FIG. 18, the signal assignments of the second terminals inthe fourth grid 753 can be a mirror image of the signal assignments ofthe second terminals in the third grid 751, where the signal assignmentsof the third and fourth grids 751 and 753 are symmetric about a verticalaxis 780 that extends in a direction 720.

Fifth and sixth grids 755, 757 of second terminals, which may overlieportions of microelectronic elements 705, 707 and be electricallyconnected therewith, can have terminals disposed in any suitablearrangement, there being no requirement to place these second terminalsin grids in which the signal assignments in one of the grids 755 are amirror image of the signal assignments of the terminals in the othergrid 757. In the particular example shown in FIG. 18, the signalassignments of the fifth grid 755 are symmetric about the horizontalaxis 782 with respect to the signal assignments of the sixth grid 757,where the horizontal axis 782 extends in a direction 722 between thegrids 751 and 757.

Also, as shown in FIG. 18, the signal class assignments of the secondterminals in the fifth grid 755 can be symmetric about the vertical axis780, and the signal class assignments of the second terminals in thesixth grid 757 can be symmetric about the vertical axis 780. As usedherein, two signal class assignments can be symmetric with respect toone another if the signal assignments are in the same class ofassignments, even if the numerical index within the class differs.Exemplary signal class assignments can include data signals, data strobesignals, data strobe complement signals, and data mask signals. In aparticular example, in the fifth grid 755, the second terminals havingsignal assignments DQSH# and DQSL# are symmetric about the vertical axis780 with respect to their signal class assignment, which is data strobecomplement, even though those second terminals have different signalassignments.

As further shown in FIG. 18, the assignments of the data signals to thespatial positions of the second terminals on the microelectronicpackage, such as for data signals DQ0, DQ1, . . . , for example, canhave modulo-X symmetry about the vertical axis 780. The modulo-Xsymmetry can help preserve signal integrity in an assembly 300 such asseen in FIG. 8A, in which one or more pairs of first and second packagesare mounted opposite one another to a circuit panel, and the circuitpanel electrically connects corresponding pairs of second terminals ofthose first and second packages in each oppositely-mounted package pair.As used herein, when the signal assignments of terminals have “modulo-Xsymmetry” about an axis, terminals that carry signals that have the sameindex number “modulo-X” are disposed at positions that are symmetricabout the axis. Thus, in such assembly 300 such as in FIG. 8A, modulo-Xsymmetry can permit electrical connections to be made through thecircuit panel so that a terminal DQ0 of a first package can beelectrically connected through the circuit panel to a terminal DQ8 ofthe second package which has the same index number modulo X (X being 8in this case), so that the connection can be made in a directionessentially straight through, i.e., normal to, the thickness of thecircuit panel.

In one example, “X” can be a number 2^(n) (2 to the power of n), whereinn is greater than or equal to 2, or X can be 8×N, N being two or more.Thus, in one example, X may be equal to the number of bits in ahalf-byte (4 bits), byte (8 bits), multiple bytes (8×N, N being two ormore), a word (32 bits) or multiple words. In such way, in one example,when there is modulo-8 symmetry as shown in FIG. 18, the signalassignment of a package terminal DQ0 in grid 755 configured to carrydata signal DQ0 is symmetric about the vertical axis 780 with the signalassignment of another package terminal configured to carry data signalDQ8. Moreover, the same is true for the signal assignments of packageterminals DQ0 and DQ8 in grid 757. As further seen in FIG. 18, thesignal assignments of package terminals DQ2 and DQ10 in grid 755 havemodulo-8 symmetry about the vertical axis, and the same is also true forgrid 757. Modulo-8 symmetry such as described herein can be seen ingrids 755, 757 with respect to each of the signal assignments of packageterminals DQ0 through DQ15.

It is important to note that, although not shown, the modulo number “X”can be a number other than 2^(n) (2 to the power of n) and can be anynumber greater than two. Thus, the modulo number X upon which thesymmetry is based can depend upon how many bits are present in a datasize for which the package is constructed or configured. For example,when the data size is 10 bits instead of 8, then the signal assignmentsmay have modulo-10 symmetry. It may even be the case that when the datasize has an odd number of bits, the modulo number X can have suchnumber.

The mirror image signal assignments of terminals in grids 714, 724, andgrids 751, 753, and grids 755, 757 may permit the above-describedreduction in stub lengths in a circuit panel, as described aboverelative to FIGS. 5-7, to be achieved when two packages 700 of likeconfigurations are mounted opposite one another on opposite surfaces ofthe circuit panel.

FIG. 18 further illustrates that one or more buffer elements 750 can beprovided as a microelectronic element disposed in a region of thepackage 700 between adjacent edges 730, 710 of the first, second, thirdand fourth microelectronic elements 701, 703, 705, and 707. Each suchbuffer element can be used to provide signal isolation between terminalsof the package, particularly for the above-noted command address bussignals received at the first terminals of the package, and one or moreof the microelectronic elements in the package. Typically, the one ormore buffer elements regenerate signals received at the first terminals,or which are received at the second terminals, and transfers theregenerated signals to the microelectronic elements in the package.

Alternatively or in addition thereto, the area of the substrate 702between the adjacent edges 710, 730 of the microelectronic elements maypermit one or more decoupling capacitors to be provided on or in thepackage in such area, the one or more decoupling capacitors beingconnected to internal power supply or ground buses of the package.

FIG. 19 illustrates a variation of the embodiment seen in FIG. 18, inwhich the positions of the first and second grids 714, 724 can be variedso as to overlie at least portions of the first and secondmicroelectronic elements 701, 703. In such case, the positions of thethird and fourth microelectronic elements 705, 707 may also change suchthat portions of first edges 730 of the third and fourth microelectronicelements 705, 707 may be moved away from the center of the package. Inthis case, the first edges 730 of the third and fourth microelectronicelements run parallel to and are spaced apart from portions of thesecond edges 712 of the first and second microelectronic elements indirection 720, such that an amount of area 760 at the center of thepackage available for connection of one or more buffer elements ordecoupling capacitors, or other device may be greater than that shown inFIG. 18.

FIG. 20 illustrates a microelectronic package 800 according to avariation of the above-described embodiment (FIG. 19). In thisvariation, the microelectronic elements 801, 803, 805, 807 are arrangedin a pinwheel-like configuration in which the first edges 810 ofmicroelectronic elements 801, 803 extend in the same direction 820 asthe second edges of microelectronic elements 805, 807. In addition, thefirst edges 830 of microelectronic elements 805, 807 extend in the samedirection 822 as the second edges 812 of the microelectronic elements801, 803. A portion of one of the first edges 810 of microelectronicelement 801 is spaced apart from and parallel to a portion of one of thesecond edges 832 of microelectronic element 807. Similarly, a portion ofthe one of the first edges of microelectronic element 805 is spacedapart from and parallel to one of the second edges of microelectronicelement 801. These relationships can be repeated within the package fora portion of one of the first edges 810 of microelectronic element 803and a portion of one of the second edges 832 of microelectronic element805, as well as for a portion of one of the first edges ofmicroelectronic element 807 and a portion of one of the second edges ofmicroelectronic element 803.

In addition, it is further seen that there is a plane 840 normal to thesubstrate which contains one of the first edges 810 of microelectronicelement 801, and which intersects the first edges 830 of anothermicroelectronic element 805. Similarly, there is a plane 842 normal tothe substrate which contains one of the first edges 830 ofmicroelectronic element 805, and which intersects the first edges 810 ofanother microelectronic element 803. From an inspection of FIG. 20, itcan be seen that a similar plane which contains one of the first edgesof microelectronic element 807 will intersect the first edges ofmicroelectronic element 801 and a similar plane which contains one ofthe first edges of microelectronic element 803 will intersect the firstedges of microelectronic element 807.

FIG. 20 further illustrates that the grids 814, 824 of first terminalshaving mirror image signal assignments may each partially or fullyoverlie one or more of the microelectronic elements in the package 800.In addition, a central region 850 of the substrate which is disposedbetween adjacent edges of the microelectronic elements, and over whichnone of the faces of the microelectronic elements is disposed, mayaccommodate one or more buffer elements or decoupling capacitors or bothas described above relative to FIGS. 18-19.

FIG. 21 illustrates a microelectronic package 900 similar to any of thepackages described above, in which the microelectronic elements 901therein are composite structures each of which can include two or moresemiconductor chips which are stacked one above the other and areelectrically interconnected with each other, and in which each may beconnected with the substrate contacts 908. Thus, in the embodiment seenin FIG. 21, each microelectronic element 901 may include a firstsemiconductor chip 932 having contacts 906 facing and joined withcorresponding substrate contacts 908 of the substrate, as well as asecond semiconductor chip 934 having contacts 910 electrically connectedwith the first semiconductor chip 932 and the substrate 902 bythrough-silicon vias (“TSVs”) 950 that extend in a direction of athickness 952 of the first semiconductor chip 932, i.e., in a directionbetween first and second opposed faces 938, 942 of the chip 932.

In a particular embodiment, the TSVs 950 can be electrically connectedwith the element contacts 908 of the first semiconductor chip 932, suchas by traces extending along a face 942 of the first semiconductor chip932. Although any electrical connections between the first and secondsemiconductor chips can be made in this manner, such connections arewell-suited for the distribution of power and ground to the first andsecond semiconductor chips. In another example, the TSVs 950 may extendonly partially through a thickness of the first semiconductor chip, andbe connected with internal circuitry within the first semiconductor chip932, rather than being connected to traces on the face 942 of the firstsemiconductor chip 932 or being connected directly to the contacts ofthe first semiconductor chip.

In the microelectronic package 900 seen in FIG. 21, each of the firstand second semiconductor chips 932, 934 can be configured such that eachsuch semiconductor chip embodies a greater number of active devices toprovide memory storage array function than any other function. Forexample, each of the first and second semiconductor chips can include amemory storage array and all circuitry required for inputting data toand outputting data from the memory storage array. For example, when thememory storage array in each semiconductor chip is writable, each of thesemiconductor chips can include circuitry configured to receive externaldata input from terminals of the package, as well as circuitryconfigured to transfer data output from such semiconductor chip toterminals of the package.

Thus, each first and each second semiconductor chip 932, 934 can be adynamic random access memory (“DRAM”) chip or other memory chip that iscapable of inputting and outputting data from the memory storage arraywithin such semiconductor chip and receiving and transmitting such datato a component external to the microelectronic package. Stated anotherway, in such case, signals to and from the memory storage array withineach DRAM chip or other memory chip may not require buffering by anadditional semiconductor chip within the microelectronic package.

Alternatively, in another example, the one or more second semiconductorchips 934 may embody a greater number of active devices to providememory storage array function than any other function, but the firstsemiconductor chip 932 may be a different type of chip. In such case,the first semiconductor chip 932 can be configured, e.g., designed,constructed, or set up, to buffer signals, i.e., regenerate signalsreceived at the terminals for transfer to the one or more secondsemiconductor chips 934, or to regenerate signals received from one ormore of the second semiconductor chips 934 for transfer to theterminals, or to regenerate signals being transferred in both directionsfrom the terminals to the one or more second semiconductor chips 934;and from the one or more semiconductor chips to the terminals of themicroelectronic package. Signals that are regenerated by a firstsemiconductor chip 932 operating as a buffer element, which are thentransferred to the one or more second semiconductor chips, can be routedthrough TSVs connected to internal circuitry, for example.

Alternatively or in addition to regenerating signals as described above,in a particular example, the first semiconductor chip 932 can beconfigured to partially or fully decode at least one of addressinformation or command information received at the terminals, such as atthe first terminals. The first chip can then output the result of suchpartial or full decoding for transfer to the one or more secondsemiconductor chips 934.

In a particular example, the first semiconductor chip 932 can beconfigured to buffer the address information, or in one example, thecommand signals, address signals, and clock signals that are transferredto the one or more second semiconductor chips 934. For example, thefirst semiconductor chip 932 can be a buffer chip that embodies agreater number of active devices to provide a buffering function intransferring signals to other devices, e.g., to the one or more secondsemiconductor chips 934, than for any other function. Then, the one ormore second semiconductor chips 934 can be reduced function chips thathave memory storage arrays but which can omit circuitry common to DRAMchips, such as buffer circuitry, decoders, predecoders, or wordlinedrivers, among others.

In such an example, the first chip 932 can function as a “master” chipin the stack and to control operations in each of the secondsemiconductor chips 934. In a particular example, the secondsemiconductor chips 934 can be configured such that they are not capableof performing the buffering function. In that case, the stackedarrangement of the first and second semiconductor chips can beconfigured such that the buffering function required in themicroelectronic package can be performed by the first semiconductor chip932, and cannot be performed by any of the second semiconductor chips934 in the stacked arrangement.

In any of the embodiments described herein, the one or more secondsemiconductor chips can be implemented in one or more of the followingtechnologies: DRAM, NAND flash memory, RRAM (“resistive RAM” or“resistive random access memory”), phase-change memory (“PCM”),magnetoresistive random access memory, e.g. such as may embodimenttunnel junction devices, static random access memory (“SRAM”),spin-torque RAM, or content-addressable memory, among others.

As further seen in the embodiment depicted in FIG. 22A, themicroelectronic package may also include through-silicon vias 960extending partially or completely through one or more of the secondsemiconductor chips 934 and may also extend through the firstsemiconductor chip 932. In a particular example, each of the secondsemiconductor chips 934 can be functionally and mechanically equivalentto any other of the second semiconductor chips. In a particular example,the first semiconductor chip 932 can be configured to regenerate or atleast partially decode received information or signals and then transferthe regenerated information or signals to the one or more of the secondsemiconductor chips 934, e.g., through the TSVs 960 between the firstand second chips 932, 934 and within the stack of second chips 934.

FIG. 22B illustrates a variation of the microelectronic package shown inFIG. 22A. Unlike the package shown in FIG. 22A, semiconductor chip 964,which can be configured to regenerate or at least partially decodeaddress information or other information, e.g., regenerate signals fortransfer to other semiconductor chips in the package, is not locatedadjacent to the first surface 108 of the substrate 902. Rather, in thiscase, the semiconductor chip 964 can be disposed at a position withinthe package that overlies one or more other semiconductor chips. Forexample, as shown in FIG. 22B, the chip 964 at least partially overliesthe semiconductor chip 962 that is disposed adjacent to the firstsurface 108 of the substrate 902 and at least partially overliessemiconductor chips 963A and 963B which are disposed atop semiconductorchip 962.

In one example, the semiconductor chips 962, 963A, and 963B may includememory storage arrays. As in the examples described above, such chips962, 963A, and 963B may each incorporate circuits configured to buffer,e.g., temporarily store, data that is to be written to such chip, ordata that is being read from such chip, or both. Alternatively, thechips 962, 963A, and 963B may be more limited in function and may needto be used together with at least one other chip that is configured totemporarily store data that is to be written to such chip or data thatis being read from such chip, or both.

The semiconductor chip 964 can be electrically connected to terminals ofthe microelectronic package, e.g., to grids in which the first terminals904 and the second terminals 906 are disposed, through electricallyconductive structure, e.g., TSVs 972 a and 972 b (collectively TSVs972), that connect to contacts exposed at the first surface 108 of thesubstrate 902. The electrically conductive structure, e.g., the TSVs972, can electrically connect to the semiconductor chip 964 throughcontacts 938 on the chip 964 and through conductors (not shown) thatextend along the face 943 of the chip 964, or along a confronting face931 of the chip 963A, or along the faces 931, 943 of both of the chips963A, 964. As indicated above, the semiconductor chip 964 may beconfigured to regenerate or at least partially decode signals orinformation that it receives through the conductive structure, e.g., theTSVs 972, and it may be configured to transfer the regenerated or atleast partially decoded signals or information to other chips within thepackage such as to the chips 962, 963A, and 963B.

As further seen in FIG. 22B, the semiconductor chips 962, 963A, and 963Bcan be electrically connected to the semiconductor chip 964 and to oneanother by a plurality of through-silicon vias (“TSVs”) 972, 974, and976 that can extend through one, two, or three or more of such chips.Each such TSV may electrically connect with wiring within the package,e.g., conductive pads or traces of two or more of the semiconductorchips 962, 963A, 963B, and 964. In a particular example, signals orinformation can be transferred from the substrate 902 to the chip 964along a first subset of TSVs 972 a, and signals or information can betransferred from the chip 964 to the substrate along a second subset ofTSVs 972 b. In one embodiment, at least a portion of the TSVs 972 can beconfigured to have signals or information be transferred in eitherdirection between the chip 964 and the substrate 902, depending on theparticular signals or information. In one example (not shown), throughsilicon vias may extend through the thicknesses of all semiconductorchips 962, 963A, and 963B, even though each through silicon via may notelectrically connect with each such semiconductor chip through which itextends.

As further seen in FIG. 22B, a heat sink or heat spreader 968, which mayinclude a plurality of fins 971, can be thermally coupled to a face ofthe semiconductor chip 964, e.g., a rear face 933 thereof, such asthrough a thermally conductive material 969 such as thermal adhesive,thermally conductive grease, or solder, among others.

The microelectronic assembly 995 shown in FIG. 22B may be configured tooperate as a memory module capable of transferring a designated numberof data bits per cycle onto or off of the microelectronic packagethrough the first and second terminals provided therefor on thesubstrate. For example, the microelectronic assembly may be configuredto transfer a number of data bits such as thirty-two data bits,sixty-four data bits, or ninety-six data bits, among other possibleconfigurations, to or from an external component such as a circuit panelthat can be electrically connected with the terminals 904, 906. Inanother example, when the bits transferred to and from the packageinclude error correction code bits, the number of bits transferred percycle to or from the package may be thirty-six bits, seventy-two bits,or one-hundred-eight bits. Other data widths are possible other thanthose that are specifically described here.

FIG. 23 further illustrates a microelectronic package 990 according to avariation of the embodiment seen in FIG. 22A. In this case, the firstsemiconductor chip 934 is interconnected with the substrate 902 in thesame manner as described above relative to FIG. 21. However, the one ormore second semiconductor chips 934 may be electrically interconnectedwith the first semiconductor chip 932 through wire bonds 925. The wirebonds may connect each second chip 934 directly with the firstsemiconductor chip 932 as shown in FIG. 23. Alternatively, in some casesthe wire bonds can be cascaded, with some wire bonds connecting adjacentsecond chips 934 together and other wire bonds connecting the first chip932 with the second chip 934 adjacent to the first chip, but notnecessarily directly connecting the first chip 932 with each of thesecond chips 934.

In the example shown in FIG. 23, the second semiconductor chips 934 areplaced with their front faces and contacts 931 thereon facing upwardly,that is, facing away from the first semiconductor chip 932. However, inanother variation seen in FIG. 24, another way the first and secondsemiconductor chips 932, 934 can be mounted together in themicroelectronic package is for each of the first and secondsemiconductor chips 932, 934 to be placed with their front faces andcontacts 931 facing downwardly, that is, towards the substrate 902. Inthat way, the contacts 931 can be electrically connected tocorresponding contacts 941 on the front face 942 of the firstsemiconductor chip 932 through wire bonds 936. In this case, thecontacts 941 can be electrically connected to the element contacts 939on the first semiconductor chip 932 such as by traces 938 extendingalong the front face 942 of the first semiconductor chip 932, with theconnections between the element contacts 939 and the substrate contacts908 being as described above relative to FIG. 21. Each second chip 934in the package shown in FIG. 24 can be connected with the first chip 932either directly by a wire bond extending therebetween or indirectlythrough a series of cascaded wire bonds, as described above.

FIG. 25 illustrates a microelectronic package according to a furthervariation of the embodiment described above relative to FIG. 22A, inwhich connections between contacts of the one or more secondsemiconductor chips 934 and the first semiconductor chip 932 can includetraces 940 which extend along one or more edges of the microelectronicelement 930, i.e., along edges of the semiconductor chips 932, 934within the microelectronic element. The electrical connections betweenthe semiconductor chips 932, 934 may further include traces 944, 946that extend along front faces of the first semiconductor chip 932 andthe second semiconductor chips 934, respectively. As further shown inFIG. 25, the front faces 942 of the second semiconductor chips may faceupwardly away from the substrate 902 or downwardly towards the substrate902.

A microelectronic package 1000 according to an embodiment of theinvention is illustrated in FIGS. 26A-26C. As seen therein, the package1000 can include a microelectronic element 1001 configured topredominantly provide memory storage array function, in that themicroelectronic element has a greater number of active devices, e.g.,transistors, configured to provide memory storage array function thanany other function, as indicated above. The microelectronic package 1000shown in FIGS. 26A-26C is similar to the microelectronic package 100shown in FIGS. 5-7, except that the microelectronic package 1000includes only a single microelectronic element 1001 configured topredominantly provide memory storage array function.

As seen in FIG. 26A, the signal assignments of the first terminals inthe second grid 1024 are a mirror image of the signal assignments of thefirst terminals in the first grid 1014. Stated another way, the signalassignments of the first terminals in the first and second grids aresymmetric about an axis 1032 between the first and second grids 1014,1024, the axis 1032 in this case extending in a direction 1042 in whichcolumns 1036 of the first terminals extend.

As shown in FIG. 26A, some or all of the second terminals 106 can bedisposed in third, fourth, fifth, and sixth grids 1016, 1017, 1017, and1019 on the second surface 1010 of the substrate 1002. In a particularcase, the signal assignments of the second terminals in the third grid1016 can be a mirror image of the signal assignments of the secondterminals in the fourth grid 1017, in like manner to that describedabove for the first and second grids. In one example, each of the fifthand sixth grids 1018, 1019 can extend in another direction 1035 which istransverse to or even orthogonal to the direction 1042 in which thefirst, second, third, and fourth grids extend. In the embodiment shownin FIGS. 26A-26C, the third, fourth, fifth, and sixth grids 1016, 1017,1018, and 1019 are each disposed adjacent a periphery 1025 of the secondsurface 1010 of the substrate 1002.

The arrangement shown in FIGS. 26A-26C, where a microelectronic packagecan include a single microelectronic element 1001 that is disposedadjacent to and electrically connected with a substrate 1002, can bemodified by making the microelectronic element 1001 a compositestructure that can include two or more stacked semiconductor ships, toproduce microelectronic packages such as those shown and described abovewith respect to FIGS. 21-25. Such embodiments including a singlecomposite microelectronic element can be the same as those shown inFIGS. 21-25, except there may be only one composite microelectronicelement structure, rather than two composite microelectronic elementsstructures as shown in FIGS. 21-25.

For example, the microelectronic element 1001 of FIGS. 26A-26C can beone of the microelectronic elements 901 shown in FIG. 21, in which themicroelectronic element is a composite microelectronic element that caninclude a first semiconductor chip 932 having contacts 906 facing andjoined with corresponding substrate contacts 908 of the substrate, aswell as a second semiconductor chip 934 having contacts 910 electricallyconnected with the first semiconductor chip 932 and the substrate 902 bythrough-silicon vias (“TSVs”) 950 which extend in a direction of athickness 952 of the first semiconductor chip 932.

In another example, the microelectronic element 1001 of FIGS. 26A-26Ccan be one of the composite microelectronic elements shown in FIG. 22A,in which the microelectronic package can also include through-siliconvias 960 extending partially or completely through one or more of thesecond semiconductor chips 934 and can also extend through the firstsemiconductor chip 932.

In a particular embodiment, the microelectronic element 1001 of FIGS.26A-26C can be one of the composite microelectronic elements shown inFIG. 23, in which the first semiconductor chip 934 is interconnectedwith the substrate 902 in the same manner as described above relative toFIG. 21. However, the one or more second semiconductor chips 934 may beelectrically interconnected with the first semiconductor chip 932through wire bonds 925. The wire bonds may connect each second chip 934directly with the first semiconductor chip 932 as shown in FIG. 23.

In one example, the microelectronic element 1001 of FIGS. 26A-26C can beone of the composite microelectronic elements shown in FIG. 24, in whichanother way the first and second semiconductor chips 932, 934 can bemounted together in the microelectronic package is for each of the firstand second semiconductor chips 932, 934 to be placed with their frontfaces and contacts 931 facing downwardly, that is, towards the substrate902. In that way, the contacts 931 can be electrically connected tocorresponding contacts 941 on the front face 942 of the firstsemiconductor chip 932 through wire bonds 936.

In an exemplary embodiment, the microelectronic element 1001 of FIGS.26A-26C can be one of the composite microelectronic elements shown inFIG. 25, in which connections between contacts of the one or more secondsemiconductor chips 934 and the first semiconductor chip 932 can includetraces 940 that extend along one or more edges of the microelectronicelement 930, i.e., along edges of the semiconductor chips 932, 934within the microelectronic element.

FIG. 26D illustrates a variation of the microelectronic element 1001shown in FIGS. 26A-26C in which contact pads 1085 of a microelectronicelement 1090 can be disposed in one or two columns 1092, 1094 near thecenter of the microelectronic element, e.g., adjacent a central axis1080 of the microelectronic element. In this example, the elementcontacts that are joined to corresponding contacts 1021 (FIG. 26C) ofthe substrate can be redistribution contacts 1088, 1089 on themicroelectronic element. Some or all of the redistribution contacts1088, 1089 that are electrically connected with the contact pads 1085can be displaced from the contact pads in one or more directions 1095,1096 along a face of the microelectronic element 1090.

In one example, the redistribution contacts 1088, 1089 can be disposedin a plurality of columns 1098, 1099 that are closer to the edges 1070,1072 of the microelectronic element 1090 than the columns 1092, 1094 ofcontact pads 1085. In a particular example, the redistribution contacts1088, 1089 can be distributed in an area array exposed at the surface1091 of the microelectronic element 1090. In another particular example,the redistribution contacts 1088, 1089 can be distributed along one ormore peripheral edges 1070, 1072 of the microelectronic element thatextend in a first direction 1095, or can be distributed along one ormore peripheral edges 1071, 1073 of the microelectronic element thatextend in a second direction 1096 transverse to the first direction1095.

In yet another example, the redistribution contacts 1088, 1089 can bedistributed along two or more of the peripheral edges 170, 171, 172, and173 of the microelectronic element. In any of these examples, theredistribution contacts 1088, 1089 can be disposed on the same face 1091of the microelectronic element 1090 as the contact pads 1085, or can bedisposed on a face of the microelectronic element opposite from thecontact pads. In one example, each contact pad 1085 can be connected toa redistribution contact 1088, 1089. In another example, there may be noredistribution contact connected to one or more contact pads 1085. Suchone or more contact pads 1085 that are not connected to a redistributioncontact may or may not be electrically connected to one or morecorresponding terminals of the microelectronic package in which themicroelectronic element 1090 is disposed.

FIG. 27 illustrates an assembly 1100 of first and second microelectronicpackages 1000A, 1000B, each being a microelectronic package 1000 asdescribed with reference to FIGS. 26A-26C above, as mounted to oppositefirst and second surfaces 1050, 1052 of a circuit panel 1054. Thecircuit panel can be of various types, such as a printed circuit boardused in a dual-inline memory module (“DIMM”) module, a circuit board orpanel to be connected with other components in a system, or amotherboard, among others. The first and second microelectronic packages1000A, 1000B can be mounted to corresponding contacts 1060, 1062 exposedat the first and second surfaces 1050, 1052 of the circuit panel 1054,respectively. The microelectronic assembly 1100 shown in FIG. 27 issimilar to the microelectronic package 200 shown in FIG. 8A, except thateach of the microelectronic packages 1000A, 1000B include only a singlemicroelectronic element configured to predominantly provide memorystorage array function.

The microelectronic packages and microelectronic assemblies describedabove with reference to FIGS. 5-27 can be utilized in construction ofdiverse electronic systems, such as the system 1200 shown in FIG. 28.For example, the system 1200 in accordance with a further embodiment ofthe invention can include one or more modules or components 1206, suchas the microelectronic packages and/or microelectronic assemblies asdescribed above, in conjunction with other electronic components 1208and 1210.

In the exemplary system 1200 shown, the system can include a circuitpanel, motherboard, or riser panel 1202 such as a flexible printedcircuit board, and the circuit panel can include numerous conductors1204, of which only one is depicted in FIG. 28, interconnecting themodules or components 1206, 1208, and/or 1210 with one another. Such acircuit panel 1202 can transport signals to and from each of themicroelectronic packages and/or microelectronic assemblies included inthe system 1200. However, this is merely exemplary; any suitablestructure for making electrical connections between the modules orcomponents 1206 can be used.

In a particular embodiment, the system 1200 can also include a processorsuch as the semiconductor chip 1208, such that each module or component1206 can be configured to transfer a number N of data bits in parallelin a clock cycle, and the processor can be configured to transfer anumber M of data bits in parallel in a clock cycle, M being greater thanor equal to N.

In the example depicted in FIG. 28, the component 1208 is asemiconductor chip and component 1210 is a display screen, but any othercomponents can be used in the system 1200. Of course, although only twoadditional components 1208 and 1210 are depicted in FIG. 28 for clarityof illustration, the system 1200 can include any number of suchcomponents.

Modules or components 1206 and components 1208 and 1210 can be mountedin a common housing 1201, schematically depicted in broken lines, andcan be electrically interconnected with one another as necessary to formthe desired circuit. The housing 1201 is depicted as a portable housingof the type usable, for example, in a cellular telephone or personaldigital assistant, and screen 1210 can be exposed at the surface of thehousing. In embodiments where a structure 1206 includes alight-sensitive element such as an imaging chip, a lens 1211 or otheroptical device also can be provided for routing light to the structure.Again, the simplified system shown in FIG. 28 is merely exemplary; othersystems, including systems commonly regarded as fixed structures, suchas desktop computers, routers and the like can be made using thestructures discussed above.

The microelectronic packages and microelectronic assemblies describedabove with reference to FIGS. 5-27 can also be utilized in constructionof an electronic system such as the system 1300 shown in FIG. 29. Forexample, the system 1300 in accordance with a further embodiment of theinvention is the same as the system 1200 shown in FIG. 28, except thecomponent 1206 has been replaced by a plurality of components 1306.

Each of the components 1306 can be or can include one or more of themicroelectronic packages or microelectronic assemblies described abovewith reference to FIGS. 5-27. In a particular example, one or more ofthe components 1306 can be a variation of the microelectronic assembly200 shown in FIG. 8A, in which the circuit panel 154 includes exposededge contacts, and the circuit panel 154 of each microelectronicassembly 200 can be suitable for insertion into a socket 1305.

Each socket 1305 can include a plurality of contacts 1307 at one or bothsides of the socket, such that each socket 1305 can be suitable formating with corresponding exposed edge contacts of a correspondingcomponent 1306 such as the above-described variation of themicroelectronic assembly 200. In the exemplary system 1300 shown, thesystem can include a second circuit panel 1302 or motherboard such as aflexible printed circuit board, and the second circuit panel can includenumerous conductors 1304, of which only one is depicted in FIG. 29,interconnecting the components 1306 with one another.

In a particular example, a module such as the system 1300 can include aplurality of components 1306, each component 1306 being theabove-described variation of the microelectronic assembly 200. Eachcomponent 1306 can be mounted to, and electrically connected with thesecond circuit panel 1302 for transport of signals to and from eachcomponent 1306. The specific example of the system 1300 is merelyexemplary; any suitable structure for making electrical connectionsbetween the components 1306 can be used.

In any or all of the microelectronic packages described in theforegoing, the rear surface of one or more of the microelectronicelements can be at least partially exposed at an exterior surface of themicroelectronic package after completing fabrication. Thus, in themicroelectronic package 100 described above with respect to FIGS. 5-7,the rear surface of one or more of the microelectronic elements can bepartially or fully exposed at an exterior surface of an encapsulant 146in the completed microelectronic package 100.

In any of the embodiments described above, the microelectronic packagesand microelectronic assemblies may include a heat spreader partly orentirely made of any suitable thermally conductive material. Examples ofsuitable thermally conductive material include, but are not limited to,metal, graphite, thermally conductive adhesives, e.g.,thermally-conductive epoxy, a solder, or the like, or a combination ofsuch materials. In one example, the heat spreader can be a substantiallycontinuous sheet of metal.

In one embodiment, the heat spreader can include a metallic layerdisposed adjacent to one or more of the microelectronic elements. Themetallic layer may be exposed at a rear surface of the microelectronicpackage. Alternatively, the heat spreader can include an overmold or anencapsulant covering at least the rear surface of one or more of themicroelectronic elements. In one example, the heat spreader can be inthermal communication with at least one of the front surface and rearsurface of one or more of the microelectronic elements such as themicroelectronic elements 101 and 103 shown in FIG. 6. In someembodiments, the heat spreader can extend between adjacent edges ofadjacent ones of the microelectronic elements. The heat spreader canimprove heat dissipation to the surrounding environment.

In a particular embodiment, a pre-formed heat spreader made of metal orother thermally conductive material may be attached to or disposed onthe rear surface of one or more of the microelectronic elements with athermally conductive material such as thermally conductive adhesive orthermally conductive grease. The adhesive, if present, can be acompliant material that permits relative movement between the heatspreader and the microelectronic element to which it is attached, forexample, to accommodate differential thermal expansion between thecompliantly attached elements. The heat spreader may be a monolithicstructure. Alternatively, the heat spreader may include multiplespreader portions spaced apart from one another. In a particularembodiment, the heat spreader may be or include a layer of solder joineddirectly to at least a portion of a rear surface of one or more ofmicroelectronic elements such as the microelectronic elements 101 and103 shown in FIG. 6.

The above embodiments can be combined in ways other than explicitlydescribed or shown in the foregoing. For example, each package canincorporate any of the types of microelectronic elements shown anddescribed above relative to FIGS. 5-7, 9, 10, 26A-26C, or any of FIG.21, 22, 23, 24, or 25, being either bare semiconductor chips, orvertically stacked and electrically interconnected semiconductor chips,or one or more semiconductor chips having a redistribution layerthereon.

As these and other variations and combinations of the features discussedabove can be utilized without departing from the present invention, theforegoing description of the preferred embodiments should be taken byway of illustration rather than by way of limitation of the invention asdefined by the claims.

It will be appreciated that the various dependent claims and thefeatures set forth therein can be combined in different ways thanpresented in the initial claims. It will also be appreciated that thefeatures described in connection with individual embodiments may beshared with others of the described embodiments.

1. A microelectronic assembly, comprising: a circuit panel having firstand second opposed surfaces and first and second panel contacts at thefirst and second surfaces, respectively; and first and secondmicroelectronic packages each having terminals mounted to the respectivepanel contacts, each microelectronic package including: amicroelectronic element having a face and a plurality of elementcontacts thereon, the microelectronic element embodying a greater numberof active devices to provide memory storage array function than anyother function; a substrate having first and second opposed surfaces,the substrate having a set of substrate contacts on the first surfacefacing the element contacts of the microelectronic element and joinedthereto; and a plurality of terminals on the second surface configuredfor connecting the microelectronic package with at least one componentexternal to the package, the terminals electrically connected with thesubstrate contacts and including first terminals arranged at positionswithin first and second parallel grids, the first terminals of each ofthe first and second grids being configured to carry address informationusable by circuitry within the microelectronic package to determine anaddressable memory location from among all the available addressablememory locations of a memory storage array within the microelectronicelement, wherein the signal assignments of the first terminals in thefirst grid are a mirror image of the signal assignments of the firstterminals in the second grid.